CHAPTER 7 - PLANTS ARE THE FOUNDATION OF NATURE

WHAT ARE PLANTS?

Plants are the eukaryotes that form the kingdom Plantae; most are predominantly photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with cyanobacteria to produce sugars from carbon dioxide and water, using the green pigment chlorophyll.  WIKIPEDIA.  Some, as we will learn and observe, are parasitic and gain all their needs from living photosynthesizing plants.

That is, fungi, lichens, and algae are NOT plants, as discussed below.

First, here are some excellent reference botanical books in the LMNGNO Resource Center library:

USEFUL WEBSITES

• Louisiana Native Plant Society – lnps.org
• Native Plant Initiative of Greater New Orleans – npi-gno.org
• USDA/NRCS Plant Guide - plants.usda.gov
• Cajun Prairie Habitat Preservation Society – cajunprairie.org
• Plants of Louisiana (keys to identify) - warcapps.usgs.gov/PlantID

Botany:  the study of plants.  A wonderful read (one of many):  In Defense of Plants, by Matt Candeias - https://www.indefenseofplants.com/

WHAT AND WHO IS A BOTANIST?

Marie Clark Taylor, Ph.D.s from Fordham and
American University.  Botany scientist at
Howard University 1945-1976.

Janakki Ammal, 1897-1984,
an imminent Indian botanist.

Joseph Hooker in the chair & Asa Gray with plant press.  

In the Rocky Mountains ca. 1877.

 
Fran McReynolds, 2016.

Carl Linné (Carl Linnaeus),

 the Father of modern taxonomy.

Jane Colden Jeune, 1724-1766,first lady

botanist in what is now the United States.

Dr. George Washington Carver.

Father Gergor Mendel.

The late Dr. Caroline Dormon, 1988-1971. A lifelong career in conservation and the leader of the effort to found the Kisatchi National Forest in Louisiana.  Her home, Briarwood near Saline, Louisiana, is now the Briarwood Nature Preserve.

Dr. Beronda Montgomery, professor and plant

biochemist at Grinnell College.  Author of Lessons from Plants.

Dr. Charles Allen, formerly at the University of Louisiana

 Lafayette and the University of Louisiana Monroe.  

He and his wife Susan operate Allen Acres Bed & Breakfast, 

which is among the top botanical training grounds in Louisiana.

Dr. Chris Reid, Louisiana State University.

Larry Allain, retired from U.S. Geological Survey, Wetlands Research Center

 in Lafayette.  An excellent prairie botanist.

The late Dr. John (John the Beloved) Thieret. Botanist and

curator of the herbarium at the University of Southwestern Louisiana

 (now University of Louisiana in Lafayette).  He taught me 440 species

of wetlands plants in four months.

The late and great Dr. R. Dale Thomas: 1936-2022. Botany

professor at the University of Louisiana Monroe from

1966-2003.   During his tenure in Monroe, he personally

collected and curated 174,000 plant specimens – the most

by a single botanist in history.  His herbarium grew

to over 470,000 specimens.  This collection is now

housed in the Botanical Research Institute of Texas in

Fort Worth.

Dr. Mac Alford, the Gentleman Botanist, professor of botany at the

University of Southern Mississippi.  An excellent field companion

everywhere, but especially in the New World tropics.

Dr. Paul Barnes, Professor and Rev. John H. Mullahy, S.J.

 Distinguished Scholar Chair in Environmental Science,

Loyola University New Orleans.  Renowned for his international

work on ozone impacts on plant communities and

his central role in informing policy development.

Dr. Steven Darwin, retired professor of botany

at Tulane University, New Orleans.

Dr. David White, retired professor in ecology at Loyola University

 New Orleans.  An excellent wetland forest botanist.

Mark Tobler, research associate with

Dr. Paul Barnes.  Plant physiology focused.

Botanical humor:  Left: Chad Chauffe, LMNGNO Certified Master Naturalist,
Spring 2019; right:  Dr. Patricia Blackwell, retired botanist from the University
of  Tennessee, and Alexandria, La native.

TOOLS OF A BOTANIST

Plant presses are for preparing plants for herbarium collections and study.

A vasculum is for collecting.  A poor-man’s vasculum is a black plastic bag!

A “field press” has a shoulder strap and is easily

managed by field botanists.

  
The plant presses above are the most traditional used.

Botanists who constantly press plants are called “hay bailers.”

A finished, mounted scientific, and cataloged plant specimen.  Note the plant specimen label in the lower

right-hand corner of the cataloged sheet.  See an example below.

LABELS SHOW ALL THE INFORMATION ON THE SPECIMEN APPENDED TO THE SHEET: name of museum where the specimen is cataloged, scientific name, family, exact locality where it was collected, ecological comments, collector, his field journal number, those accompanying him on the collection trip.  Missing from this label is the museum catalog number.

WHAT IS A PLANT?

Oxford Dictionary definition:  a living organism of the kind exemplified by trees, shrubs, herbs, grasses, ferns, and mosses, typically growing in a permanent site, absorbing water and inorganic substances through its roots, and synthesizing nutrients in its leaves by photosynthesis using the green pigment chlorophyll. Exceptions include the Indian pipe shown below, and dodder vines we commonly observe in our region..

When we say plants, what is included?

• Vascular plants:  Possessing xylem and phloem vessels that disseminate fluids and nutrients throughout their bodies.
• Nonvascular plants: These plants have no xylem or phloem, so there are other adaptations for moving fluids and nutrients.

THE LARGEST LIVING ORGANISM ON EARTH

To make this determination, one must ascertain if the target species is only one individual (using DNA samples) and how much area does it cover.  It is also good to know the age of the population, but if only interested in “what is the largest,” this may not be necessary.

It is interesting that if we ever think of large plants we focus on sequoia trees and other large woody plants.  In fact the largest living organism now known to humans is said to be the marine seagrass fibre-ball or ribbon weed, Posidonia australis, discovered in Shark Bay, Australia.  It is considered a hybrid species, having 40 chromosomes (its presumed parental species each have 20 chromosomes).  Scientists think this gigantic individual is 4,500 years old, and it asexually spreads by rhizomes, not seeds.  It covers an unbelievable 70.2 sq. miles (44,928 acres).

Posidonia australis, Shark Bay, Australia.  Photo by Rachel Austin,

University of Western Australia.

Before it was discovered in 2020, the largest organism known to humans was a fungus, Honey or Humongous fungus Armillaria solidipes, in the Malheur National Forest in Oregon, whose mycelium covers 3.9 sq. mi (2,496 acres) and is 2,400-8000 years old.  No photos since the mycelium is below ground!

Another “large species” is a forest of Quaking Aspen, Populus tremuloides, called the Pando Aspen Clone, in Fishlake National Forest in central Utah.  The Pando Aspen Clone consists of  47,000 aspen trees all growing from a single root that is believed to be the result of a single aspen seed that germinated 2.6 million years ago at the beginning of the Gelasian Stage of the Pleistocene.  The Pando forest covers 1.2 million acres.

Da Winna!  The Pando Aspen Clone.  Photos from Wikipedia.

WE WILL LEARN MANY WAYS TO IDENTIFY PLANTS:

• Flowers
• Vegetative characters/appearance
• Bark
• Boles
• By habitat
• Dead
• Feel/touch
• Aroma/odor
• Sounds (walking through or rolling a part between your fingers)
• Seeds
• Speed as you pass by (is it a 70 mph plant, or a 20 mph?)
• In context of species around it
• Salinity
• and much more

WILL BEING A STUDENT OF PLANTS ALTER MY DAILY HABITS?

YES, INDEED.  You will become very aware of plants you learn and those you don’t know.  As you walk down a sidewalk or through a field, you will find yourself identifying plants.  You will return home and dig through field guides and google plant groups.  You will begin to plan trips by developing a “target list” (a list of species you want to see).  As your skills progress, you will become able to recognize species as you speed down a highway - sugarcane, roseau cane, fields of Ranunculus sardous in spring, Packers glabellus in winter and early spring, Circium horridulum, vast stretches of Spartina alterniflora, bottomland hardwoods, and much, much more.  It will build as an obsession, and you will be a better person for it!  We call these and other species “70 mile and hour plants - for others you will learn to slow down for a better look!

LET’S CHARACTERIZE PLANT COMMUNITIES:

• They are not inanimate
• They are working together as a community
• Members are in constant communication
• The members are nurturing one another
• The community has or is undergoing plant succession
• Members of the plant community are engaged with the mycorrhizal community
• There is intense ”warfare” (competition) taking place in what seems a peaceful setting

GROWTH FORMS OF PLANTS

• Trees
• Shrubs (bushes)
• Vines
• Epiphytes
• Submerged aquatic vegetation (SAV)
• Emergent aquatic vegetation (EAV)
• Epiphylls
• Flotant marsh associations
• Parasites (Mistletoe, dodder)

MAJOR GROUPS OF “PLANTS” (all of these were called plants in the 1960s).

• Fungi (not a plant)
• Lichens (not plants)
• Slime molds (not a plant)
• Algae (not plants)
• Bryophytes, liverworts, hornworts (non-vascular plants - see discussion below)
• Vascular Plants (see discussion below)

• “Ferns and fern allies”
• Grasses
• Rushes/sedges
• Angiosperms
• Gymnosperms

EIGHT PLANT FAMILIES HAVE COMMONLY USED SYNONYMS THAT ARE APPROVED FOR INTERCHANGEABLE USE BY THE INTERNATIONAL CODE ON BOTANICAL NOMENCLATURE

• Gramineae and Poaceae - grasses
• Leguminosae and Fabaceae - legumes
• Compositae and Asteraceae – composites/asters
• Palmae and Arecaceae - palms
• Umbelliferae and Apiaceae - umbellifers
• Labiatae and Lamiaceae - mints
• Guttiferae and Clusiaceae – tropical trees
• Cruciferae and Brassicaceae - mustards

ALLELEOPATHY

Most of us rarely consider that plants have to compete among themselves for space, sunshine, nutrients, and other vital resources. Some methods that may come to mind are different growth rates and variation in leaf arrangement, shape of crown, and overall height.

One way that may be surprising is termed allelopathy, or a plant’s production of its own herbicides. These phytotoxins, or “plant killers,” inhibit the growth of other types of plants. Their production is more common in desert regions since rainfall often washes them from the soil and provides a good substrate for microbial degradation. There are, however, a number of plants in the New Orleans area that use allelopathy.

The oaks and magnolias are good examples. They produce tannins that ward off encroaching competitors. Many of us have tried in vain to grow grass in their shade. We have raked, planted, fertilized, added soil, and prayed, but with rare success. Since all of a tree’s resources must come from the area reached by its roots, typically under its foliage, it should not be surprising that they have developed a means to keep other plants out of their “pantry.”

Another example is golden rod, a beautiful bright yellow fall flower that grows in open, sunny places. The phytotoxin produced by these plants inhibits the growth of woody plants such as trees. When you think about it, it makes sense that a plant requiring an abundance of sunlight would have a method to prevent itself from being shaded out by taller, more permanent plants.

These phytotoxins have received little public attention to date, but in the future humans will surely make more use of Mother Nature’s safe herbicides.

THERE ARE MANY WAYS TO CHARACTERIZE PLANTS:

DICOTYLEDONS (DICOTS)

• Broad leaves
• Leaves with netted veins
• Flower parts 4 or 5
• Have vascular cambium, so their girth can grow

MONOCOTYLEDONS (MONOCOTS)

• Narrow (grass-like) leaves
• Leaves with parallel veins
• Flower parts 3 or 6
• No vascular cambium – don’t grow in girth

ELEMENTARY PLANT ANATOMY

WE TEND TO VIEW TREES FROM THE GROUND UP

BUT THIS IS WHAT THE WHOLE ORGANISM LOOKS LIKE

ROOTS:  THERE ARE MANY FUNCTIONS

• Functions:

• Anchor, support, stability of the plant
• Absorption and conduction/transport of fluids for the plant
• Storage
• Photosynthesis (in aerial roots)
• Movement
• Reproduction
• Communication and nurturing one another

ROOTS:  THERE ARE MANY FORMS

• Tap roots –
• Fibrous roots –
• Cauline roots – roots growing from stems & vines
• Aerial roots – roots above the ground; most are also adventitious roots
• Adventitious roots – growing down off stem from non-root tissue, on orchids, hanging from vines
• Pneumatophores – black mangrove
• Rhizomes – run beneath soil and sprout
• Stolons – stems run across the surface and place roots at their nodes
• Bulbs - an expanded portion of a stem that is the resting stage of certain plants, like onions, swamp lilies, and the like.
• Prop – grow down from a plant and give support where it touches the ground.

FIBROUS & TAP ROOTS ARE COMMON

Aerial roots on tropical fig trees                     Aerial roots on wild grape vines

Cauline roots                                                Prop roots

WHY DO PRAIRIES HAVE SUCH DENSE GROWTH IN SEEMINGLY DRIER HABITATS

Note the depth relative to exposed plant size and density of their roots.

THIGMOTROPY - trees whose roots touch hard substrates tend to spread out and grow over the surface.  When you drive down St. Charles Avenue, note how this happens over curbs by live oaks.

BOLE(=TRUNK) OF A TREE

Fluted base of the bole of American elm        trees.

BUTTRESS BASES & ROOTS:  exaggerations of fluted bole bottoms

Buttressed tree bases in Cockscomb Basin, Belize – ceiba (l) & kaway (r)

Buttressed base & knees of Bald Cypress

TUPELO GUM BOLE BASE – NOT FLUTED – although there may be minor fluted features.  Typically they smoothly enlarge toward their base.

PERIDERM (AND BARK)

• Outermost layers of the plant are called the periderm
• Bark (a nontechnical word) - outermost layer of woody plants’ (trees, vines, shrubs) stems, roots, trunk (bole)
• Periderm is all tissues outside the vascular cambium, and they are formed by another cambium, the cork cambium
• Inner bark is living tissue and includes the innermost periderm
• Outer bark is dead tissue, and all tissues are at the outside of the periderm – this is what we traditionally call the “bark”

BARK

 “Alligagtor” bark of Common Persimon

                Scaly bark of Pecan

TWO PLANTS WHOSE LEAVES & FRUITING BODIES ARE SIMILAR, but their bark is diagnostic for identification

Musclewood, Carpinus                Eastern Hophornbeam, Ostrya
(note the fluted bole)

BRANCHES

Majority of branches come off.   Furrowing of bark on bole continues
of the bole at 90. Black gum,       onto the branches, Shumard Oak,
Nyssa sylvatica.                        Quercus shumardii.

PLANT ANATOMY AND FUNCTION IS EXTREMELY VARIABLE AND COMPLEX.  NOT “ONE SIZE FITS ALL” – AND WITH EXCEPTIONS TO EVERY OBSERVED PROCESS AND STRUCTURE!

VASCULAR vs. NONVASCULAR PLANTS

• Plants with a vascular system – composed of xylem & phloem – that moves fluids (water, nutrients, food, minerals) and gasses around in the plant – similar in function to human veins, arteries, & capillaries
• What are examples of vascular plants?

• Angiosperms
• Gymnosperms
• Ferns
• Clubmosses
• Horsetails

NON-VASCULAR PLANTS

• Plants with no vascular system – no xylem and phloem.
• They do not circulate fluids, instead they just absorb them through their leaflike scales.
• Types:

• Mosses (Bryophytes)
• Liverworts (Marchantiophyta)
• Hornworts (Anthocerotophyta)

HOW DOES A PLANT GROW?

• Which part is where growth actually happens?

• In the meristem

• Apical meristem
• Bifacial (lateral) meristem (vascular cambium)

• Growth in the body of the plant

• Vascular cambium – growth of the xylem & phloem
• Cork cambium – growth of the periderm/sheath of the plant

STRUCTURES & FUNCTIONS IN STEMS & ROOTS

• Xylem – Continuous throughout the plant and is located nearer the center (adaxial), this vascular tissue moves water and some nutrients, water and some nutrients up through the plant.  Water not used is released, called transpiration, through stomata on the bottom of leaves.
• Phloem - located near the outside of the stem (abaxial), this vascular tissue aids in support and moves fluids (photosynthate), including sugars and other nutrients, downward from the leaves to tissues throughout the plant.  This process is called translocation.

In leaves, the adaxial side is usually the upper surface of the leaf, and the abaxial side is typically the lower surface of the leaf.  This explains why aphids and other invertebrate plant predators are often found on the lower surface of leaves, because that is the abaxial surface where the sugar-carrying phloem is near the surface.

PHLOEM & XYLEM COMPARISONS

• Phloem                                                Xylem

• Food & nutrients                                - Water & minerals
• Moves up or down stem, from leaves        -Moves down the plant’s stem, but In roots, stems, leaves                        there is some upward movement
• In roots, stems, leaves                        In roots, stems, leaves
• Not star-shaped                                -Star-shaped
• Forms vascular bundle with xylem        -Forms vascular bundle with
• On outer side of vascular bundle                 phloem, and walls contain lignin

 which gives strength to the stem

-In center of vascular bundle

HOW XYLEM & PHLOEM WORKS

VASCULAR CAMBIUM & BUNDLES

Phloem and xylem occur in vascular bundles, zones in the plant tissue that additionally consist of supportive and protective tissues.

F – vascular cambium; E – phloem; D – xylem; E+F+D – vascular bundles.

IT IS REALLY MORE LIKE THIS

CORK

• Cork layer (phellum) – just beneath the epidermis – cork produced in the cork cambium
• Corky wings on species such as winged elm, sweetgum, and strawberry bush (Euonymous)

Strawberry bush, Euonymus americanus         Sweetgum, Liquidambar styraciflua

Winged elm, Ulmus alata

MORE GENERAL WORDS REGARDING PLANTS, ESPECIALLY TREES

• Sapwood – So named due to the flow of water (xylem) and food items (phloem), located in the outer areas of the bole or twigs under the park and cork cambium.
• Heartwood – Over time, as the tree ages, the vascular system fills in with gums, resins, oils, tannins, and such, and water no longer flows through this zone.
• Annual rings – Tree growth responds to drought and cold periods by cells not growing as large (getting smaller), so experts can examine a cross-section of a bole, count rings, and estimate age and environmental conditions experienced.

PITH

• Soft, specialized cells (parenchyma) that are in the center of the stem (most commonly observed) that are soft and spongy.  Store and move nutrients.  If they deteriorate, then the plant is left with a hollow core.
• Best example in our workshops – Black elderberry, Sambucus nigra.  

 
No, this is a           Pith in the center of
pith “helmet”          Elderberry

TRANSPIRATION

• The release of moisture by the plant that is coming up the xylem – a plant “transpires”
• On a hot day, stand under a large tree and note that transpiration make it very cool
• Stomata – openings on the bottom of leaves through which the moisture escapes during the day
• Lenticels – pores on the stems that allow gas exchange through the cork.  Very important because the phloem is very metabolically active and needs O2 coming in and CO2 going out.

STOMATA – openings on the lower surface of leaves – gases and water pass these “gates,” normally during the day – they are closed at night.

LENTICELS - places where plants allow gases to escape to the atmosphere.

Lenticels are quite obvious on black elderberry, Sambucus nigra.

GUTTATION

• Xylem sap (looks like clear water) that forms drops on the tips of leaves.  
• Common in grasses but occurs in other plants.
• Most plants close their stomata at night, so transpiration does not occur
• If soil is very moist, the roots absorb water at night – since stomata are closed, pressure builds throughout the xylem pathways and is exuded at the tips of leaves through specialized organs called hydathodes, or water glands - appear as drops of “water.”

Photosynthesis is the process by which plants use sunlight to manufacture food.  It can be quite complex, but a great and well written source is How Plants Work:  The Science Behind the Amazing Things Plants Do by Linda Chalker-Scott.
See cover of the book at the beginning of this chapter.

Types of photosynthesis:

• C3 – This is the most common form in our area and is most efficient when there is adequate water and CO2.  An enzyme (RubisCo) releases O2 through the stomata of the leaves and the carbon atoms are linked to form sugars.  Think nice, healthy, robust yard grass in spring & summer.
• C4 – Tends to be present in hot, dry habitats or periods where plants may keep their stomata tightly closed.  Think yard weeds in late summer & fall.
• CAM (Crassulacean-acid metabolism) – Mostly in desert plants where water is normally scarce. Think cacti.

FLOWERS

The world’s smallest flower, which has no petals – Wolffia sp., watermeal or mudmidget.  Native in the southern states.

The world’s largest flower, parasitic corpse flower:

Corpse flower, Rafflesia arnoldii.  Common name is from its horrible odor.  Sumatra.

Some argue that the largest is also from Sumatra, and is the Giant Corpse Flower, Amorphophallus titanium.

FANCIFUL TRUFFULA TREE FOREST - Dr. Seuss

FLOWERS

STRUCTURE

ADD THE RECEPTACLE – just an expanded point of attachment – a platform for attachment.

REMINDER:

FEMALE STRUCTURES ARE PISTILS

MALE ARE STAMEN

ONE HOUSE, TWO HOUSES, OR A GOOD OLE NOLA DOUBLE?

MONOECIOUS SPECIES (“ONE HOUSE”):  Both male and female reproductive structures on the same plant, but in different places.  Examples:

• LIVE OAKS:  male catkins, female acorns
• MOST PINES:  smaller pollen bearing male pine cones (microsporanglate strobilus) & larger seed-bearing female pine cones (megasporanglate strobilus)

DIOECIOUS SPECIES (“TWO HOUSES”):  Male and female reproductive structures on different plants.  Examples:

• BACCHARIS:  Plants with all male flowers (small, yellowish) or all female flowers (white that look like grass skirts).  These often dominate the roadsides during the fall.
• ILEX: We will often see Ilex vomitoria and Ilex decidua (and maybe other species).

SYNOECIOUS (HERMAPHRODITIC, BISEXUAL [SORTA] SPECIES) (“GOOD OLE NOLA DOUBLE”):  The norm for most of our plants – both male and female structures in the same flower.  Examples:

• Almost all of the common flowers around us – hibiscus, marsh mallow, spiderwort, maples trees, magnolias, bulltongue, etc.

 REGULAR = ACTINOMORPHIC = RADIAL SYMMETRY – cut through most axes and you get equal halves

IRREGULAR = ZYGOMORPHIC = BILATERAL SYMMETRY – cut down the middle and get equal halves – cut any other way and you don’t

Identical twins, different color blooms.  Tucks Parade 2025.

Parts of the Iris Flower - All these terms/structures are preset on all iris species (quoted direct from leonineiris.com)

• Spathe: The papery covering surrounding emerging buds. It turns brown and protects the ovary as it develops.
• Standards: The three upright petals of the iris flower.
• Falls: The three lower petals of the iris flower that may either hang down or flare out.
• Beard: The fuzzy "caterpillar" from which bearded iris get their name. They are found at the base of the falls, tucked in towards the center of the flower. They are also found on the inside of the standards of some species of aril irises.
• Haft: The hafts are the base of the falls and standards where they begin narrow near the center of the flower. In older cultivars and some species the hafts of the falls are often marked with veins and lines. Flowers so marked are sometimes referred to as being "hafty" and it is often considered a fault unless it pleasantly adds to the distinctiveness of the flower.
• Pistil: The female reproductive structure of a flower which in iris consists of ovary, style-arms and stigma.
• Ovary: The ovule-bearing part of the pistil at the base of the iris flower which develops after fertilization into the seedpod containing seeds derived from the ovules.
• Styles: The part of the pistil that rises from the ovary and bares the stigma. In the iris, it branches into three flat arms that may or may not be the same color as the petals.
• Style Crest: The flared end of the style arm, usually split into two projections and often serrated.
• Style Arm: Three style arms rest above the anthers; may be the same or contrasting colors as the iris flower.
• Stigma: The part of the pistil that receives the pollen. In the iris, it is a lip projecting from the under side of the style arm, below the style crest.
• Stamen: The. male reproductive structure of a flower consisting of a filament, and an anther containing the pollen grains. They rest between the style arms and the falls.
• Anther: Stiff, fuzzy stem-like appendage holding pollen grains, located under the style arm.
• Signal: On beardless irises there is often a signal consisting of a bright contrasting spot of a different color that replaces the beard.
• Crest: Instead of a signal or a beard the crested or Evansia irises of the Lophiris section have a ridge or cockscomb of petal like material called a crest.
• Spur: A short side stem that may or may not be near the top of the stigmatic lip.
• Stigmatic Lip: The lip-like petal under the style crest which receives the pollen.
• Space Age Iris: These irises have horns, spoons or flounces extending out from the end of the beard
• Horned: Horned iris have petal extrusions below the beard that curve up and away from the fall to form a pointed horn.
• Spoons: Spoons are long stringy filaments that extend out from below the end of the beard and are tipped by small, cupped petaloids.
• Flounces: Iris with flounces have multi-petaled fan shaped appendages without beards that arise from the center of the fall.
• Perianth Tube: The bases of the petals join together into a tube that surrounds the style and extends down to the ovary. Some species, such as Iris unguicularis, have very long perianth tubes that replace the stem and extend down to the ovary which is at ground level.

COMPOSITES ARE DIFFERENT

• Remember, members of the Compositae can correctly be call Asteraceae
• Most call their flower “composites”
• They reproduce the same way as those just studied, but they have two parts that are totally composed of individual florets (small “flowers”) – called inflorescences:

• The disc (or disk) in the center, composed of tube-like florets clustered together, are complete flowers
• The ray florets (or ligules) are the circle of often yellow parts that look like petals, but each is generally sterile.

• Of course, they show more complexity than the norm
• Advantage of composites:  when visited by an insect, many clustered florets are fertilized making them super efficient reproductively

THE HEAD OF A COMPOSITE IS CALLED A CAPITULUM

A ZINNIA FROM MY GARDEN

A BIT MORE ON COMPOSITES

EXAMPLES OF COMPOSITES

Vincent van Gogh & his sunflowers, Rex parade 2025.

FLOWER ARRANGEMENT TERMINOLOGY

A scorpioid cyme, Heliotropium indicum. A real beauty!

FRUITS

Dehiscent fruits have seeds in a seedpod that splits open to release seeds (milkweed seeds).

Indehiscent fruits are not in a seedpod and simply disperse when they are ripe (red maple samaras).

TYPES OF FRUIT

PLANT CHARACTERISTICS

LEAVES

FIRST – THE LONGEST LEAF IN THE WORLD:
Japanese climbing fern,  Lygodium japonicum –
each “vine” is a single leaf – can grow to 100 ft long-
introduced, first recorded in the U.S. in Georgia in 1903.

ABSCISSION:  THE REASON THAT LEAVES FALL

Why do leaves fall off plants and how does it happen? First, all plants shed their leaves. The most obvious are the so-called deciduous trees like pecans, sycamores, cypress, tupelo, and elm, all of which shed all their leaves at once in the late fall. Others, such as magnolia, live oak, and wax myrtle, are non-deciduous and shed their leaves as each leaf reaches old age, though many oaks have two times during the year when they drop a lot of leaves during a short period of time.

To explain why leaves fall, imagine a hackberry during summer. Each leaf has a complete connection with the circulatory system of the tree and there is a free exchange of water and nutrients. At the base of the leaf, near the stem, there is an area known as the abscission zone. To the casual observer, the abscission zone doesn’t appear different from adjacent portions of the leaf, but microscopic examination reveals fiberless cells that are smaller than those of neighboring areas.

With decreasing day length in autumn, a number of chemical changes occur within the abscission zone and two distinct layers of cells form.

The first, the separation layer, is characterized by short cells with thin walls. These characteristics render the separation layer weak and the weight of the leaf, often helped by a breeze or rain, causes it to fall from the stem.

The second is the protective layer which is formed by the deposition of fatty material within and between the cells on the stem side of the separation layer. This is the so-called leaf scar which is so obvious on stems of deciduous plants during the winter months. If one looks closely one may see tiny dots which represent bundle scars, the ends of veins which previously carried nutrients to the living leaf. Sometimes these bundle scars appear to form animal faces within the leaf scar.

Late this autumn, on a crisp morning when there is a nice new leaf fall, reflect on the physiological phenomena precipitating the shower of leaves.

LEAF ARRANGEMENT ALONG A STEM

Opposite leaves roughleaf dogwood, Cornus drummondii (left),

alternate leaves, southern sugarberry, Celtis laevigata, (right)

MORE LEAF ARRANGEMENT

SIMPLE vs. COMPOUND LEAVES

NOTE THE AXILLARY BUD

AXILLARY BUD OF AMERICAN BEACH, Fagus grandifolia.

LEAF SCAR (NOTICE THE BUNDLE SCAR)

SIMPLE LEAF

American elm, Ulmus americana – drip tip, doubly serrate margins, and uneven

base at petiole (the last is a character of all elm species’ leaves).

SIMPLE LEAF TYPES

MORE ON SIMPLE LEAF SHAPES

Eastern Cottonwood , Populus deltoides. 

Sweetgum, Liquidambar styraciflua.

Water oak, Quercus nigra.

Eastern redbud, Cercis canadensis.

Tree Huckleberry, Vaccinium arboretum - smooth margins,

sharp tip on the leaf.

RED VS. WHITE OAK LEAVES

Both are lobed:  red (L) has spine-like tips to lobes, white (R) are rounded.

MORE ON DIFFERENTIATING RED & WHITE OAK

RED OAK

• See leaves above
• No tyloses so wood is more porous, and water can move through it, and it is prone to rot
• No medullary rays so wood is without cross-stripes and such

WHITE OAK

• See leaves above
• Have tyloses that close cellular structure making it water & rot resistant
• Have prominent medullary rays that produce distinctive, decorative ray & fleck pattern when wood is quarter sawn

WOOD GRAIN IMAGES OF RED & WHITE OAK (PLACE IN TWO COLUMNS SIDE-BY-SIDE AS ON SLIDE)

• Red oak with open pores:

• White oak with tylose- filled pores:

Tyloses are in the xylem of whiteoak (absent in red oaks).  In the case

of drought or infection, they block

movement and protect the tree.

THAT SAID, IS THIS A RED OR WHITE OAK?

IT IS A Quercus virginiana, A LIVE OAK – A MEMBER OF THE WHITE OAK GROUP

Don’t be frustrated – experience helps you understand!

LEAF TOPS & BOTTOMS

LEAF MARGINS

AN EXAMPLE OF HOW LEAF MARGINS AND THEIR ONTOGENETIC (CHANGE OVER TIME) NATURE BECOMES IMPORTANT FOR SURVIVAL

Some plants exhibit what is called phenotypic plasticity.  They may have predictable, purposeful variation of leaf margins (as well as other anatomical and physiological features).  An easily observed example along our trails is seen in growth changes of live oaks, Quercus virginiana.  When they are young, they are a prime food source for browsers such as white-tailed deer, so they grow spinate (spiny) margined leaves.  As they age and grow higher, they lose the spine structures and have smooth margins (which gives them more photosynthesis surface and less energy producing the spines).

Botanists often use the word heteroplasty (heteroplastic development or vegetative phase change) when there is a general shift change from juveniles to adult form.

Coquille Trail new live oak growth.  Note the spinate

margins of the lower leaves.

It’s clearly in their genes, since this image was taken on St. Charles Avenue

 and we rarely encounter white-tailed deer there!

LEAF VENATION

                               Palmate                             Pinnate                          Arcuate

MULTIPLE LEAF SHAPES ON A SINGLE PLANT

Sassafras, Sassafras albidum.                     Red mulberry, Morus rubra

HIGHLY VARIABLE ONTOGENETICALLY:  WATER OAK, Quercus nigra

CONFUSION:  PAPER  MULBERRY , Broussonetia papyrifera - introduced

CONFUSION:  WHITE MULBERRY, Morus alba

CONFUSION:  RED MULBERRY, Morus rubra – possibly of hybrid origin in our area

COMPOUND LEAVES

ARRANGEMENT AND COMPOSITION

TYPES OF COMPOUND LEAVES

TRIFOLIATE LEAF

MYCORRHIZAL NETWORKS

• Associations among plants in which their roots are united via the hyphae of an array of mycorrhizal fungal mycelia – the purpose is the movement of nutrients, water, carbon, nitrogen.
• This means that anytime we walk through a forest, we are treading across myriad “holding hands” of communication!

MYCO-HETEROTROPHIC PLANTS

• No photosynthetic activity, so totally dependent on mycorrhizal networks for food.
• Indian pipe, Monotropa uniflora, native to north Louisiana and surrounding areas.

“SMOKING AN INDIAN PIPE”

RANCHERS AND FARMERS KNOW THAT CERTAIN TREES HAVE A ROT RESISTANT HEARTWOOD AND MAKE GOOD FENCE POSTS.

FENCE POSTS (PLUS THIS IS THE PUNCH         

LINE TO A JOKE FOR 5-YEAR-OLDS)

TWIGS - VERY IMPORTANT TO IDENTIFY PLANTS IN WINTER.

GALLS - FOR MORE INFORMATION AND VIEW OF DIVERSITY VISIT CHAPTER 8 UNDER INSECTS

• An interaction between insect eggs and plant tissue into which they were laid.  A gall is fundamentally formed as the plant rapidly encapsulates the egg so that it does minimal damage to the plant.  Such symbiotic relationships develop over a millenia.  AND, they are species specific between insect and plant.  SEE THE GALL SECTION IN THE CHAPTER ON INVERTEBRATES.

A SELECTION OF CYPRESS GALLS – Each is stimulated by a different species of midge fly, most of which are undescribed species.  If you want to see them in the wild, take a fall walk among the cypress trees in New Orleans City Park along Marconi, Harrison, and Diagonal streets.

OUR MOST COMMON LIVE OAK GALLS – stimulated by cynipid wasps.

Live oak twig gall, caused by the fall/asexual generation of the cynipid wasp Disholcaspis cinerosa.

Live oak wool bearing gall, caused by the asexual phase of the

cynipid wasp Andricus quercuslaniger.

MITE (undescribed species of the genus Acalitus) GALLS ON JESUIT’S BARK, Iva frutescens.

PHYTOTELMS – holes in trees that are habitats/ecosystems for a variety of critters.

A ONCE ENJOYABLE PHYTOTELM AT THE BEGINNING OF THE COQUILLE TRAIL

IMAGE WITH AN EVENING RESIDENT CAROLINA WREN

INSECTIVOROUS PLANTS

• Adapted to living in low nutrient, acidic environments.  
• In our region, they are restricted to “bogs” and “pine flatwoods,” both being infertile, weathered, acidic, and hydric. All are in western Louisiana, north of Lake Pontchartrain, and throughout the southeastern U.S.

• Bogs - Most are hydrated by precipitation and groundwater, are acidic and nutrient-poor with heavy peat accumulation.  Those with open water in the center tend to be “dystrophic,” due to low dissolved oxygen and poor nutrients.  In western Louisiana, where there are sandstone and clay lenses, and the Florida parishes, their source of water may be hillside seepage, depending on belowground geology preventing downward movement of water.  These habitats may have pitcher plants.
• Pine flatwoods - These are hydrated by surface sheet runoff.  Their pitcher plants are present in these habitats to the east, but not in savannahs in the western parts of the state.

• All species have mechanisms that capture living prey, which they digest and assimilate their amino acids.
• They have digestive fluids.

Pitcher Plants: have fluids in the throat of their modified leaf (the “pitcher”) and downward pointed trichomes to prevent prey escape.  

The last image is of a Saracenia alata pitcher that was knocked down by turkeys, torn open, then the insect contents were mostly devoured.  Carriere, Mississippi.

SUNDEWS –GOBLETS OF STICKY DIGESTIVE FLUID ON TIPS OF TRICHOMES

BLADDERWORTS, Utricularia sp. - uses suction to suck food into a digestive chamber – this mechanism is in the vegetative parts

A flowering, floating portion of the plant.

An enlarged view of the bladders that capture prey.

THORNS, SPINS, PRICKLES, TRICHOMES

• Thorns are modified branches/stems, may have a leaf, are derived from shoots, and have vascular bundles inside.  If not modified, then always on the stem.
• Spines are modified leaves, or extensions of leaf veins; they may or may not have vascular bundles inside.  Are always on the stem.
• Prickles are extensions of the cortex or epidermis and lack vascular bundles.  May be on stem, fruit, or leaf.

THORNS

• Modified stem, so they are located at a node where a branch should be.
• May be branched (spines and prickles never are).
• Examples:  honeylocust, Cretaegus species, Pyracantha.

SPINES

• Modified leaves so they are located where leaves should be found, just above a lateral branch, or if modified stipules they may be at the base of a leaf on stem.
• Examples:  sweet acacia, Opuntia cactus, osage orange, Parkinsonia, and trifoliate orange.

The spines on Opuntia and other cacti are modified leaves (the pad is the stem).

Areoles are a bump on a cactus that has spines growing from it.

Spinescent leaf margin, as in American holly, Ilex opaca.

PRICKLES

• Outgrowth of epidermis on stems, leaves, or petioles
• Usually randomly spaced where they occur – more organized if on margins of leaves (these may be called spines, and the leaf is said to be spinescent)
• Leaves – American holly
• Stems – dewberries & blackberries, horse nettle, thistle, smilax, toothache tree, devil’s walking stick, roses.

Dewberries/blackberries, Rubus sp.

TRICHOMES

• Normally small, hair-like outgrowths of the epidermis.  Not rigid, but effective against small invertebrate herbivores.  Erroneously called “hairs” due to their resemblance.  We all slip with this terminology occasionally.
• Toxic fluids on the trichomes may cause stinging or itching.  If causing these sensations, they are termed urticating trichomes/hairs.  Since the toxins are “injected” into the skin, Dr. Charles Allen calls plants having these structures “venomous plants.”

Salvinia minima and S. molesta are introduced, invasive floating ferns whose surfaces are covered by vertical trichomes.

Note the texture of the Salvinia minima surface due to the presence of trichomes.

VINING METHODS - HOW DO VINES CLIMB?

Look closely and determine if the vines climb with twists that are clockwise, counterclockwise, alternating, or just climb straight up the bole.

To determine, imagine turning the bole toward your eyes and discerning the twisting direction.

Clockwise vining

Counterclockwise vining

Counter- and clockwise  - Trumpet creeper, Campsis radicans.

VINE ATTACHMENTS FOR CLIMBING

Catclaw, Dolichandra unguis-cati – they are called “catclaw” due to their sharp hold-fast mechanism.

Crossvine, Bignonia capreolata, have sharp pointed holdfasts.

Trumpet creeper, Campsis radicans, use these holdfast mechanisms (cauline roots, arise from the vine) at spaced nodes.

New growth Virginia creeper, Parthenocissus quinquefolia, have little “fingers” with terminal pads to hold their vines to the trunk.

Old growth Virginia creeper, Parthenocissus quinquifolia, have dense “fingers” (cauline roots) to hold their eventual massive vines to the trunk.

Carolina moonseed, Nephroia (Cocculus) carolina – native, twine around their support – counterclockwise.

Muscadine, Vitis rotundifolia, native, also twines around – clockwise.

Poison ivy, Toxicodendron radicans, uses small “hairs” (rootlets) to cling to a tree.

Smilax and passionflower use curly tendrils to hold on to their support.

PHENOLOGY/SEASONALITY

• This is a thread in our overall educational program and will be covered in many workshops.

ALLELEOPATHIC COMPOUNDS – SURVIVAL IN THE WAR AMONG PLANT SPECIES

• Chemicals produced by a plant to inhibit growth of competing plants

• Goldenrods need open, non-shaded places to grow.  They produce alleleopathic compounds that inhibit woodY tree growth
• Tannins produced by live oak trees inhibit all sorts of plant growth under their drip line

PLANT SUCCESSION

The sequence of species colonization as conditions become good to support new species.  Each stage is called a sere, or seral community.  

PLANT SUCCESSION FACTS

• Primary succession – starting from barren ground.  Lengthy, due to lack of good, nutrient-rich soils.
• Secondary succession – applies to the path forward in seral stages when there is better soil and seeds present.
• Each habitat zone/location has its own succession process – ending at a specific climax stage

SEQUENCE OF SUCCESSIONAL ARRIVAL OF PLANTS

• Pioneer species
• Grasses
• Shrubs
• Forest species
• Dominance by climax species

• Swamps:  Bald Cypress, Tupelo Gum
• Cheniers/ridges:  Live Oaks
• Bottomland hardwoods:  Dwarf Palmetto, a variety of hardwoods
• Upland forests:  highly diverse species of trees
• Brackish marsh:  Spartina patens
• Salt marsh:  Spartina alterniflora

ALL OF THAT SAID, ONE OF THE DRIVERS OF SUCCESSION IS DAMAGE TO VEGETATION – LIKE HURRICANE IDA

Both of the above photos were taken on U.S. 51 near Manchac.

HABITAT STRATEGIES

• Habitat strategies

• Rainforest – light penetration to ground, importance of vines, drip-tip leaves, laterite soils
• Desert/beach – succulents
• Elevation/latitude – tundra plants, etc.

INTERESTING PLANT STORIES THAT ARE FUN!

HOW TO REMEMBER THE DIFFERENCES AMONG GRASSES, SEDGES AND RUSHES

GRAMINOIDS” – AN EXAMPLE OF LOOKING AT CONFUSING GROUPS

• Poaceae (Gramineae) - grasses
• Cyperaceae – sedges
• Juncaceae - rushes

SEDGES HAVE EDGES

RUSHES ARE ROUND

GRASSES HAVE JOINTS (WHEN THE COPS AREN’T AROUND

ICE RIBBONS

One of our favorite fall bloomers in white crownbeard, Verbisina virginica, that some astute, observant local naturalists call frost flowers, even though the popular pentas exhibit the same tendencies.  Under certain conditions during freezing weather, one might find them with stem cracks exuding thin ice ribbons.  The ice is composed of sap and is quite lovely, although it may only last one day if the temperature rises.  

What makes them appear?  It may be predictable when the soil is warmer than the air as the freeze sets in.  Often, it occurs on the second night of a freeze.  The first night the sap in the stems expands and creates cracks.  On the second night the sap squeezes out through the stem cracks in differing forms.  The rest is up to Mother Nature and temperature.  The ice ribbon beauty is captivating..

Ice ribbons on pentas in Metairie.

Ice ribbons on white crownbeard, Jean Lafitte National Park, Barataria Unit, January 2014.  
Photos by Charles Butler.

HONEYLOCUST, Gleditsia triacanthos

New growth.                                             Mature tree.

SUGARBERRY (SOUTHERN HACKBERRY), Celtis laevigata - note the corky wart-like protuberances.

KALALOCH or “TREE OF LIFE” - sitka spruce, Picea sitchensis, Olympic National Park.

PALM-LIKE PHONE TOWER – there is one on the West Bank near the elevated expressway and one near Tiger Stadium in Baton Rouge.

Phoenix, Arizona

Corner of Bob Pettit Boulevard and Nicholson

 (La. 30) near L.S.U.

SUGARCANE

Our ubiquitous sugarcane, Saccharum officinarum, is a major agricultural produce and not native to Louisiana.  Naturalists often need to understand such plants and their habitats in order to properly see their relevance to other species.

Certified Master Naturalist Emma Reid standing in sugarcane.

The species was brought to Louisiana in 1751 by Jesuit missionaries.  Today 500,000 acres of sugarcane exist in Louisiana alone.  It is harvested in fall - especially October.  The fields are often burned, and immediately replanted for the following year.  They are not only farmed in broad reaches of fields, but the crop is so valuable that farmers may plant rather small, odd shaped areas alongside highways.

Harvested sugarcane stems (culms) are transported to sugar mills where the canes are run through heavy rollers  to release the liquid sugarcane juice.  This is then spun in machinery to remove the pure liquid and the result is a brown sugar.  A byproduct called bagasse (pronounced locally as “ bag ass”) is produced in enormous amounts.  If you drive past a sugar mill, search for brown bagasse piles the size of buildings!  There are growing numbers of uses for bagasses including biofuels, energy, heating, tableware, electricity, insulation, composting, and the like.  If you want to be a billionaire, discover a new use that is cheap to produce!!!

From internet.

Products that are locally popular for consumption include cane sugar and especially cane syrup.

Google sugarcane if you are interested in the technicalities of industrial production.

OUR SMALLEST NATIVE PLANT FLOATING COMMUNITIES:  Duckweed, a Liverwort, and two fern genera:  Salvinia and Azolla.

Louisiana is blessed with wonderful biodiversity at all levels.  We tend to move through our wetlands and focus on the largest species, but by simply stopping, kneeling by the water, and looking closely at what might be floating on its surface, a whole new botanical world opens.

MORE ABOUT DUCKWEEDS - THE SUBFAMILY LEMNOIDEAE OF THE FAMILY ARACEA (FORMERLY FAMILY LEMNACAE):  NATURALISTS JUST CALL THEM “DUCKWEEDS.”

Duckweeds are a group of plants that are generally tiny, yet they have all the features of flowering plants and are modified for floating.  Being minute they may disappear among densely growing large aquatic plants.  

Back at the beginning of my (Bob’s) career as a biologist, I was fortunate to have a professor, the late and beloved Dr. John Thieret, and fellow student, the late and admired Dr. Howard Clark, who were experts on the Lemnaceae.  Howard's master's thesis was The Lemnaceae of Louisiana at the University of Southwestern Louisiana (now The University of Louisiana-Lafayette).  The fact that I was often in the field with these two botanists required that I get excited about these floating miniatures, and their enthusiasm guaranteed that even I would occasionally abandon my pursuit of amphibians and reptiles in deference to itsy-bitsy plants.

The genera of the duckweeds are rather easy to identify, but the species can be confusing.  Their anatomy consists of one or more small leaf-like fronds, or thalluses.

As a group, they are simply called duckweed.  That said, local lore provides a bit of diversity.   My friend, Gary Uhl, calls duckweed "peanut grass."  Botanist Dr. Charles Allen mentioned that some in our state call duckweed coverage of water "Louisiana snow."  He also has heard people call watermeal (Wolffia, see below) "grits," which is descriptive.  Jerald Horst, an extant naturalist of the highest order, told me that many in his circle call duckweed "water lily seeds," thinking they are the seeds of water hyacinths.

There are five genera, and despite all the local names, each genus has its own official common name:

• Lemna - duckweed - one root per frond
• Spirodela - duckmeat - two roots per frond
• Landoltia - dotted duckmeat - two to five roots per frond
• Wolffiella - mud midget - flat, often spiraled, without roots
• Wolffia - watermeal - round, oval, or elliptical, without roots; the smallest form

Since they are so small, duckweed prefers water that is either still or slowly flowing in ponds, lakes, canals, and bayous.  All float at or near the surface, taking advantage of air sacs called aerenchyma.  They may be found mixed in with other plants in otherwise open water, or they may reproduce rapidly and cover the surface, with one or a combination of species and genera.  They typically are one plant thick on the surface, but winds may push them into thick piles at pond margins.  Eventually, these will either sink or spread back out to a thin layer.  They may live on moist soils if forced off the water surface by a boat wake or storm.

Duckweeds are flowering plants.  In fact, Wolffia is the smallest flowering plant in the world and produces the smallest fruit.  They have simple inflorescences which extend from a cavity in the surface of the frond and consist of one or two staminate flowers and one pistillate flower.  They rarely set seeds for some reason.  When they do, each fruit, depending on the species, contains 1-5 seeds.  The seeds have no flotation, so they sink to the bottom.

Typically, they reproduce asexually.  The "mother" frond begins to bud from a meristematic-zone (a place in plants where undifferentiated cells are found and growth takes place).  The "daughter" frond exits laterally from a pouch and remains appended to the mother by a connecting stipe until it is mature, at which time it breaks away.  By this time, the former daughter has probably already produced its own daughter fronds.

This process is rapid.  Various species can double their coverage of habitat every two days.  One species of Wolffia in India can bud a new daughter frond every 30 hours, meaning that one mature frond can, in four months time, produce offspring (with each offspring producing offspring) that are equal in volume to that of the earth!  Thankfully, this hasn't happened.

Each species can produce only a certain number of daughter fronds before becoming senescent.  These are easy to recognize because they yellow and appear desiccated.

A number of species produce turions.  These starch-filled, rootless morphs function in overwintering by sinking to the bottom and lodging in mud.  I'm not sure how common this is in our region, since it is normal to find various duckweed species on the surface in all types of winter weather.

Duckweed is eaten by many organisms that share their aquatic habitats.  Since they float, they don't need or have much fiber, and they are rich in nutrients, including amino acids that are animal-like.

In fact, it is always fun to find animals that live in duckweed-covered habitats that are densely coated with species of the Lemnaceae, especially snakes, alligators, and turtles.

Duckweed covered venomous cottonmouth (left, photo by Mike Downie) and alligators (right).

And speaking of being rich in nutrients, Nature Note reader Isabelle Cossart, proprietor of Isabelle's Orange Orchard in lower coast Algiers in New Orleans, shared that the only fertilizer she uses in her orchard of 550 trees is duckweed, which she harvests from a moat that surrounds her home.   That is a wonderful new approach to sustainability!

There are a number of nice duckweed sources of information available on the internet, but Wayne Armstrong's Treatment of the Lemnaceae and The Charms of Duckweed are excellent with many nice macrophotos.

If you would like to have a digital copy of The Lemnaceae of Louisiana (which was never published) by Howard Clark, let me know.

Let’s take a look at some of the species:

Common duckweed, Lemna minor.  This is our most abundant species of duckweed.  Its pale green color differentiates it from Salvinia species.

Lemna minor, Photo by Neal Kramer.

Lemna minor (pale green), Salvinia minima (darker green), and Wolffia columbiana (dots).

Roadside ditch, Manchac.  November 2013..

Lemna minor (large) and Wolffia columbiana (tiny dots) in L.S.U. Lake

near I-10, Baton Rouge, December 2021.

Dotted duckmeat, Landoltia punctata - formerly in the genus Spirodela.

Dotted duckmeat, Landoltia punctata.  Photos by Asit K. Ghosh (left) and Ricky Taylor (right).

Common duckmeat, Spirodela polyrrhinza

Common duckmeat, Spirodela polyrrhinza, New Orleans City Park, March 2018.  Note how thin the leaf is, and the delicate roots that hang in the water.

Columbian watermeal, Wolffia columbiana - small dots on the water’s surface

Columbian watermeal, Wolffia columbiana, L.S.U. Lake at I-10, October 2021.

Florida mudmidget, Woliella gladiata - floating below the water’s surface

Florida mudmidget, Wolffiella gladiata, Shell Bank Bayou, November 2012 (right), 2017 (left).

Left photo by Emma Reid.

SIMILAR IN APPEARANCE, BUT NOT RELATED:  Cat-foot ricciacarpus, Ricciacarpus natans, a freshwater floating liverwort.

Cat-foot ricciacarpus, Ricciacarpus natans, a liverwort.

Atchafalay River Basin, May 1990.

A few Ricciacarpus natans with many Lemna minor.  Barataria

Unit around Coquille Trail, March 1981.

HOW TO DISCERN WHETHER FLOATING SMALL PLANTS ARE SALVINIA (A FERN) OR DUCKWEED (FLOWERING PLANT)?

In the photo below, note the two floating together:

• The relatively thick, round, dark green leaves with trichomes on their surface are waterspangle, Salvinia minima.  These are ferns and mostly reproduce by budding, a form of vegetative or asexual reproduction
• The smaller, thinner, smooth surfaced light-green leaves are duckweed, genus Lemna (of which there are several species, but they all share these characteristics).  They are flowering plants so reproduce as do other such plants.

Salvinia minima (large, round) and a common duckweed, Lemna minor (small, light green).

THE POTENTIAL SCURGE OF THE LOUISIANA WETLANDS, COMMON SALVINIA OR WATER-SPANGLE, Salvinia minima

This floating fern is normally found in association with giant salvinia, mosquito fern, and species of duckweed.  It grows rapidly asexually by budding and fragmentation,  but spore-containing sporocarps can be present on leaves.  They spread over  surfaces exponentially and, if wind blown, can become very thick on the surface, thus preventing oxygen exchange and aquatic animals not being able to access air.  It has been seen over one foot thick, and may either remain that way or, when the wind changes course, rapidly spread to new areas.  They are readily spread also by various animals.  They can attach to wading birds, and hitch hike to the next feeding area. or take a ride on the back of an alligator, turtle, or snake.  Humans get involved when they fish in an area with salminia, then move their boat to another wetland venue without cleaning salvinia away.  The mode of transport is unending.

Salvinia minima along Coquille Trail, with a pig frog peaking out.

Salminia minima with obvious trichome texture on leaf surfaces.

Dense growth of Salvinia minima at Shell Bank Bayou, in 2012

Most people think they are flowering plants like our miniscule duckweed, but they are not.  They are classic ferns.  If you examine their leaf surfaces, they are covered with vertical ornamentation called trichomes.  Duckweed never have these structures.

Trichome (not “hairs”) are different in apical structure  between common and giant
salvinia.  Be sure to look with a magnifying loupe when examining them.

They arrived in the U.S. from South America in the 1920s and 1930s, and were first found near Franklyn, Louisiana, in 1980.  Botanist Garrie Landry reported them in 1981, but assumed that they had been there for some time before being discovered.

By the late 1980s, Salvinia minima had spread coast wide and beyond.  By the 1990s the populations became so dense that botanists worried that they would become an ecological disaster.  We opined that with the rapid loss of coastal wetlands, salvinia might eventually have a positive effect on the availability of organic matter to support inshore and offshore fisheries.  During the 20 teens, populations began to decline.  No empirical information exists for the cause, but it may just be a cycle or possibly insects or other predators were taking hold.

Regardless of how we consider salvinia populations, they are probably here to stay - yet another established invasive species.

GIANT SALVINIA, Salvinia molesta

There is a new invasive aquatic plant in town! It is Giant Salvinia, Salvinia molesta, a native of South America that is the first cousin of another invasive that has been clogging our waterways for a number of years, Water-spangle, Salvinia minima.

Compare the leaf structure and size of this Salvinia molesta to that above of Salvinia minima.

Egg beater trichomes of Salvinia molesta.  Photo by Barry A. Rice,
The Nature Conservancy.

Giant salvinia was first discovered in the U.S in South Carolina in 1995, and in Toledo Bend, Louisiana in 1998.

A floating fern, giant salvinia grows quickly, doubling its biomass about every week. This rapid growth, coupled with the fact that there are no natural predators in our waters, makes this species dangerous to local ecosystem health. It occludes the surface of the water, thus shading out subsurface vegetation and preventing oxygen exchange between the air and waterways. It can get two to three feet thick, making it impossible for turtles and the like to get a breath of air, otters and alligators to swim and capture prey, and humans moving about in boats. It quickly clogs drain pipes, and changes the hydrology of wetlands by impeding the flow of water. Heavy infestations can literally kill fisheries and the nursery grounds upon which they rely.

It is surmised that the species’ invasion began by someone dumping aquarium vegetation in the water. This species reproduces entirely vegetatively; its spore capsules do not produce spores in North American populations.

It has spread by simply floating along rivers and bayous, traveling from site to site on the bottoms of boats and trailers, and even on the backs of alligators.

It has been a bit controlled by use of herbicides and the introduction of the Australian salvinia weevil, Cyrtobagous salviniae.

What about this idea? Sautéed salvinia, Rio Grande perch, and apple snails with penne pasta?

Yum!

A LOVELY FLOATING FERN, MOSQUITO FERN, Azolla caroliniana

The tiniest fern in the world is alive and well in New Orleans! The mosquito fern (Azolla caroliniana) is a small floating plant species that may cover the surface of still waters much as does duckweed. The name mosquito fern derives from the belief that mosquitoes cannot lay their eggs in water covered by these diminutive plants.

Mosquito fern is olive green in spring and early summer. By mid-summer and extending into winter, the leaves add anthocyanins, thus causing the surface of roadside ditches covered by mosquito fern to appear red.

Mosquito fern, Azolla caroliniana, on L.S.U. Lake at I-10, Baton Rouge.  October 2021.

Azolla caroliniana, August 2008.  Photo by Shannon Fortenberry.

Azolla caroliniana before it turns totally red.  Photo by Larry Allain.

Mosquito fern does not fill a normal fern niche and its 1/32nd of an inch wide overlapping leaflets are not visually impressive, but this tiny plant is important in the food market of many undeveloped countries. Each leaflet has a pouch which contains a symbiotic blue-green alga (Anabaena azollae) which converts atmospheric nitrogen to a form that can be used by other plants. The fern uses a portion of the nitrogen as it becomes available and when the plant dies and settles to the bottom, it releases the remaining nitrogen for use by other organisms. A good example of human application of this phenomenon is that rice paddies in southeast Asia may be covered with mosquito fern during the early growing season, producing as much as 40 lb of nitrogen per acre. As the rice grows, the ferns are shaded, die and sink to the bottom, thus recycling the vital nutrient to the food crop. Commercial fertilizers are produced at great expense and are virtually unavailable to undeveloped countries.

When present, mosquito ferns give our farmers the same advantages.

The mosquito fern is one of Mother Nature’s natural sources of cost-free fertilizer.

MEDIUM PLANT FLOATING COMMUNITIES

In the “small floating communities” above, the plants are purely floating and not rooted to the bottom.  The following is a discussion of medium-sized floating leaves that are all rooted in the bottom.

American spongeplant, Limnobium spongia

These two-inch in diameter floating leaves on the surface as they develop, with the  aid of air containing “bladders” on the venter of the leaves.  As they age, they emerge from the surface and the floatation system disappears.  They are not super-abundant in our region, but are occasionally encountered.

American spongeplant, Limnobium spongia:  left to right - bladders to support
floatation, starting to lift from the water surface, then full growth.

Typical Limnobium aggregation on the water.  February 2013.

Flower of Limnobium spongia.  August 2014.  

FLOATINGHEARTS, Nymphoides sp. - we have three species in our state

Nymphoides have relatively small flowers compared to Nymphaea odorata and other species of the genus.  These have oval floating leaves about three inches in diameter.  One is introduced, Nymphoides peltata, with yellow flowers.

Yellow floatinghearts, Nymphoides peltada.

Dense growth of Nymphoides peltata near Krotz Springs.  August 2013.

POTAMOGETON

Potamogeton nodosus.  Wax Lake Delta, April 2021

Waddill Wildlife Refuge, Baton Rouge.

MYRYOPHYLLUM

LARGE PLANT FLOATING COMMUNITIES

WATER-SHIELD, Brasenia schreberi

Among our most easily identified floating-leaved aquatic plants is water-shield, Brasenia schreberi, of the family Cabombaceae (some place it in the Nymphaeaceae). It is widely distributed, and occurs in 42 states, including Alaska, and the majority of Canada. The species is also native to Central America, northern South America, the West Indies, Asia, Africa, Australia, and beyond. Water-shield leaves are oblong and three- to four-inches long. Its leaf stalk (petiole) attaches in the middle of the leaf, umbrella-like, and extends to the muddy bottom where it originates from a running stolon.

Oval floating leaves of water shield, Brasenia schreberi, in a pond with
a lone round leaf of Nymphaea odorata and a solitary Utriculata flower
emerging from the depths.

Preferred habitat includes relatively clear lakes, ponds, and slow moving streams. In our area, it is found north of Lake Pontchartrain, most commonly in waterways rich in tannins. Water-shield prefers rather shallow water up to six feet deep.

The petioles and undersides of the leaves are maroon, and they are coated with a gelatinous film. This clear, slimy, jelly-like substance is slippery, but not sticky. No other floating leafed plant in our area has this characteristic. Oddly, it is difficult to find information on the function of the slime. You might assume it protects the petioles and leaves from certain underwater predators.

Closely examine the petiole under the maroon leaf venter.  It is
coated with a non-sticky gelatinous covering.  Very slippery.

Water-shield flowers are emergent, dull purple, and bloom in late spring and summer. Small beetles and/or the wind pollinate them. Each flower's ten or more fruit are small, ovoid, and each contains two seeds that are released underwater when the fruit tissue decomposes. The plants also commonly reproduce asexually as the stolon grows through the substrate.

Water-shield is known to have phytotoxic (toxic to plants) properties. They kill certain algae and bacteria, as well as some vascular plants. This allelopathic (plant killing) nature may explain why the water around their colonies is usually clear and open.

The Japanese are fond of eating water-shield leaves in salads. They harvest the unfurling leaves as they ascend through the water column. The species also has medical applications, with the astringent qualities of the leaves used to treat boils and related infections.

A number of animals, including certain ducks, feed on water-shields. Because it grows densely, while leaving exposed water surface due to its relatively small leaf size, water-shield communities tend to have abundant submerged animal communities. They are good for "perch jerking."

The only negative I have heard is that their growth inhibits swimming. I can attest, however, along with my botanical mentor, the late Dr. John Thieret, that swimming through a dense growth of water-shield is an exhilarating experience!

MORE FERNS

CEMETERY FERN, Pteris vittatus

One of the most conspicuous forms of vegetation in urban New Orleans is the fern that grows on walls in the Vieux Carré and on tombs in our cemeteries. The most widely used name for this species is Ladder Brake (Pteris vittatus), but it is locally known as Cemetery or Cistern Fern due to its habit of growing in these two moisture retaining areas.

Cemetery fern, Pteris vittatus, New Orleans Botanical gardens.

Ladder Brake is native to southeastern Asia and its present range in the U.S. extends from southwestern Louisiana to South Carolina and southward throughout Florida. No one knows when or how it crossed the Pacific. Some say that Ladder Brake escaped from cultivation and established itself in suitable habitat. Others have a more intriguing explanation for its arrival that accounts for its greatest abundance centering in the cemeteries. As the story goes, vases received from southeastern Asia were securely packaged in excelsior which was replete with Ladder Brake spores. As the vases were unwrapped and placed in cemeteries and courtyards, the spores were introduced to favorable habitat and germinated, thus beginning the life cycle of the Ladder Brake in the New World.

In New Orleans, as elsewhere, the growth of the Ladder Brake is confined to substrates rich in lime (calcium carbonate). It seems that our local soils lack an adequate amount of this necessary compound while mortar, especially the eighteenth and nineteenth century clam and oyster based variety, provides an excellent substitute.

RESURRECTION FERN, Pleopeltis polypodioides

Among the romantic images of the deep south are splaying live oak limbs covered with Resurrection Fern (Pleopeltis [old name was Polypodium] polypodioides), emerald green bunches of tightly clustered fronds.

Resurrection Ferns are epiphytes (=air plants), so called because they grow on other plants (most often Live Oaks and Cypress).  They have running rhizomes that creep along the tree’s branches, with fronds sprouting along the way.  They gather their nutrition from dust and other organics that settle on the branches, and their water is absorbed from the tree’s surface and the humidity in the air.

Since the symbiotic relationship between the fern and its host tree results in the fern benefiting (a place to live, gaining nourishment from elements collecting and moving along the tree’s bark) while the host is not affected at all, the relationship is called commensalism (if the fern benefited and the host was damaged, the relationship would be called parasitism; if both benefited, it would be mutualism).

During moist weather, Resurrection Ferns are open in full glory.  On older trees, they can appear so dense that one expects the limb to collapse.  However, huge clusters are quite light since there is no significant weight to their network of thin roots that snake through the rough bark substrate.

As the air dries due to the lack of rain, the fronds appear to shrivel and die as they turn brown and curl. This is a near perfect adaptation to conserve vital moisture during otherwise taxing periods of drought.  The visual effect is strikingly different from the lush green growths that are customary in south Louisiana’s normally humid weather.  But, all it takes is a nice rain and the fronds reabsorb water, slowly regain their deep green coloration, and uncurl to their customary flat fronds.  Of course, this is the origin of the name – the seemingly dead fronds appear to come back to life.

Resurrection fern, Pleopeltis polypodioides.  When it dries, it appears dead;
when it (or its parts) gets water it renews its beauty.  Audubon Park, May 2024.

Since they grow on limbs and trunks, their niche is characterized by light filtered through the host tree’s canopy.

As other ferns, Resurrection Ferns reproduce by spores which are produced in sporangia.  Clusters of sporangia appear as small dark dots called sori that line the lower surface edges of the fronds.

Resurrection ferns are one of the few larger plants that have traveled to outer space during experiments on their abilities to perform under weightless conditions.

The next time you see Resurrection Ferns, you should see them both as a beautiful plant and as a species with exceptional adaptations for living in an environment with huge swings in rain and humidity.

EPIPHYTES & EPIPHYLLS

One of the magical views in the southern United States is a forest festooned with Spanish moss. Many believe that this moss (actually a member of the pineapple, or bromeliad, family) is parasitic on the tree, but it is not. It simply uses the tree as a resting place, and is not connected to the tree’s circulatory system at all.

Epiphytic Spanish moss, Tillandsia usneoides.

Such plants are called epiphytes – plants that simply grow upon other plants. Temperate zones are not characterized by an abundance of epiphytes, so those that occur are notable. An uncommonly seen, yet very interesting, epiphyte in Louisiana is the Green Fly Orchid, Epidendrum magnoliae, found cryptically living on the trunks of tupelo gum and magnolias.

Green fly orchid, Epidendrum magnoliae,
Pearl River in Louisiana.

If you want to see epiphytes in all their glory, visit the tropics. The species diversity is immense and their weight borne by the limbs of rainforest trees is enormous. As one would expect, the diversity of many types of living things, including frogs, spiders, insects, butterflies, and more, increases sharply in response to the epiphytic jungle’s myriad of niches.

A related biota is the epiphyllus community. Epiphylls are species that live on the surfaces of leaves, thorns, spines, twigs, and the like. They include tiny plants, algae, and microbes of all sorts.

Epiphyllus growth on magnolia leaf.

Plants everywhere have epiphyllus communities, and the casual observer rarely notices their presence.

It is the bacterial epiphylls that cause frequent, and often nasty, infections from puncture wounds by spines in the tropics.

The next time you walk a forest for the pure pleasure of the surroundings, think not just of the trees, but of the true diversity of the forest. Above ground, that includes rooted vegetation of all types, plus the epiphytes and epiphylls.

EXTRAFLORAL NECTARIES

One of the most interesting areas of ecology is the study of relationships between plants and insects.

The study of relationships between living organisms is called symbiosis. If both benefit from the relationship, it is called mutualism. If one benefits and the other is unaffected, it is called commensalism. If one benefits and the other is hurt, it is called parasitism.

An interesting symbiotic association occurs in my backyard and in local fields each summer. Passion flowers (Passiflora incarnata) in one’s yard are both a blessing and a curse. The blessing is that they have beautiful flowers and attract fritillary butterflies. The curse is that, like most vines, they constantly spread about, popping up everywhere.

One of the fun things about passion flowers is that they have little raised pores near the base of each leaf that exudes nectar.

Nectar is a sweet liquid that attracts birds and insects to their flowers so that these animals will spread pollen from plant to plant.

Since these nectar pots of the passion flower are not in the vine’s flowers, they are called “extrafloral nectaries.”

An ant feeding at an extrafloral nectary on the vine of a
purple passion flower, Passiflora incarnata.

One rarely finds a useless structure in nature, and extrafloral nectaries are no exception. Their sweet fluid is a very attractive food source for certain species of ants. While visiting the plant for a sweet sip (the invertebrate equivalent of a drive-in daiquiri shop), the ants cleanse the vine of fungal spores, grazing insects, and other artifacts of nature that may inhibit the plant’s growth.

This is a classic example of mutualism – the plant is protected and the ant obtains sustenance.

Extrafloral nectaries are also found on the common Partridge Pea (Cassia fasciculata), and they serve the same function to the plant.

These structures are common in the tropics, with classic examples such as Bullhorn Acacia (Acacia cornigera), in which the ants live in expanded bases of thorns and swarm out when anything moves the plant. Their bites and stings are very effective in defending their symbiotic homes.

Do yourself a favor and look closely at plants. You will certainly see adaptations that give them protection or make them better adapted for their habitats.

WHY DO SOME PLANTS FLOWER BEFORE THEY LEAF OUT?

All New Orleanians know that the late winter-very early spring transition is the time when a number of our favored urban horticultural species and more rural native trees flower brilliantly.  For the most part their flowering occurs before they produce leaves.

Classic examples we see in February and March include Callery Pears (Pyrus calleryana; several cultivars are used locally), Redbud (Cercis canadensis), Drummond Red Maple (Acer rubrum var. drummondii), several species of native plums (Prunus sp.), Pecan (Carya illinoinensis), Live Oaks (Quercus virginiana), and more.

Our most obvious early flowering horticultural tree is “Japanese Magnolia,” a common name actually used for two species of Asian origin:  1) Saucer Magnolia, Magnolia xsoulangiana (often misspelled as M. xsoulangeana), a hybrid derived most commonly from a combination of M. liliiflora and M. denudata, and having dark pink to white flowers with shorter petals giving them a cup-shaped flower; and 2) pure Magnolia liliiflora (Lily or Tulip Magnolia), which has deeper purple and longer petals forming a more pitcher-shaped flower.  Both of these descriptions were shared by the gentleman botanist Dr. Mac Alford, of the University of Southern Mississippi.

Saucer magnolia, Magnolia xsoulangiana, blooming in February and March.

Lily magnolia, Magnolia liliiflora, in bloom in February and after leafing out in May.

There are other related species used in horticulture, but these are our commonly used species.

We normally see plants begin their vegetative growth each season, become well established, then put energy into their most important job - reproduction.  This makes sense, because this common approach establishes the plant, which may have died back during winter, and thus provides the nutrition basis to redirect energy to the huge task of producing seeds.

Over the winter these species reach differing levels of dormancy.  They have, however, adequate stores of carbohydrates that will be important in launching their spring growth.  Since reproduction is so important, the adaptive strategy of pre-leafing flowering is to use those energy stores to produce flowers that provide the seeds.

Additionally, the production of flowers requires sunlight, just as does the production of leaves.  Early flowering ensures that the leaves will not block the sunlight from the flower buds.  Once the flowers have done their jobs, they fall and leaves appear.

The grand strategy is that these plants put all food reserves into reproduction before all the other plants begin to grow, then spend the rest of the growing season focusing on growth and storing food for the winter.

Next time we have a hurricane (heaven forbid) or very strong fall storm, note that some trees have a survival response by either flowering out of season (Japanese Magnolias) or producing new leaf growth (Bald Cypress, Taxodium distichum).  These are simple survival responses, but important enough to the species that do this to make them risk using valued energy stores.  Why take the risk?  Possibly to ensure they produce a new seed crop or have new leaves for boosting food stores late in their growth seasons.

L.S.U. AgCenter Consumer Horticulture Specialist Dr. Dan Gill has written about the Japanese Magnolia-hurricane relationship in his column in The Times-Picayune.  He notes that the plant’s new buds have formed by fall, and a storm blows the leaves off, exposing the buds to direct sunlight.  The fall Japanese Magnolia flowers are paler than the winter/spring flowers since the heat destroys many of the purple pigments.  Sadly, new buds will not form after a fall flowering, so the intensity of the next winter/spring bloom will be diminished.

Such is Nature!

WHY DO SOME PLANTS DROP THEIR LEAVES IN EARLY SPRING?

A great local example is the live oak, Quercus virginiana.  they drop their leaves in late winter/early spring at the same time they are producing copious amounts of pollen.  The reproductive strategy is to enhance the ability of pollen from their male catkins to easily reach their female pistillate or coon flowers.  They are borne on breezes passing among the leafless branches.  This happens quickly, and the tree produces more leaves to resume photosynthesis.

Quercus virginiana, live oak, during pollination before new leaves appear.

New Orleans City Park, Louisiana, near Big Lake.  March 12, 2022.

IT’S NEVER TOO LATE TO ENJOY THE YELLOW COLORS OF SPRING:  TWO SPECTACULAR SPECIES OF WILDFLOWERS

A drive across our state in April suggests that the season’s primary color is yellow - horizon to horizon.  There is also a mix of blue, white, purple, and red, but yellow covers the largest percentage of the landscape.

Have you seen the expansive yellow covered fields?  They seem to be most of the fallow agricultural zones, especially between Lafayette and Alexandria, and on to Shreveport.  It is amazing how a non-native species can spread so widely and with such high densities. In New Orleans, the best views are the buffer zone between Allen Toussaint Boulevard and City Park’s northernmost golf course.  The same is true on a lesser scale along the northern reaches of Marconi between Allen Toussaint and Harrison.

Hairy buttercup, Ranunculus sardous, fields just north of Golden Meadow, April 2014.  scenes like this are abundant way past north Louisiana in spring.

The bright yellow is caused by dense growths of one species – Hairy Buttercup, Ranunculus sardous. This species appears low to the ground, about six inches tall, and the flowers are just above the tufts of leaves.  In spite of being one of our most abundant spring flowers, Hairy Buttercup is an introduced species that is native to Europe and has spread around the world.  It is very showy in New Zealand pastures, as an example.

Just for fun, its Finnish name is “Etelänleinikki” and its Dutch name is “Behaarde boterbloem.”   These make even Ranunculus sardous seem easy – unless you are Finnish or Dutch.

We are talking about “real” buttercups – the yellow kind.   Do not confuse real buttercups with the pink to white Mexican Evening Primroses, or Pinkladies, Oenothera speciosa, that some call “buttercups.”  They are distinct and unrelated, but have been called buttercups for generations.  We used to ask kids to smell evening primrose “buttercups,” then jam them into their noses that were left covered with yellow pollen.  This is our most prevalent buttercup memory!

Hairy buttercups, Ranunculus sardous (yellow), blooming with Pinkladies or Mexican
primrose, Oenothera speciosa, (pink), in New Orleans City Park in March 2015.

 Louisiana has about 10 species of Ranunculus, but all the fields I’ve investigated were primarily R. sardous.  This observation has been verified by the well known botanists Dr. Charles Allen and Dr. Chris Reid.

As in other species of this genus, buttercups are toxic when eaten.  They contain ranunculin, which when the plant is wounded or chewed releases the toxin protoanemonin.  This toxin causes nausea, burning of the mucus membranes when ingested, and when it comes in contact with the skin may cause itching, rashes, blisters and other such effects.

There is yet another abundant yellow flower in spring, but it is most common in moist ditches, although it may occupy fields as well.  It may well be the most economically important wildflower in Louisiana.  It is commonly called Yellow-top or Butterweed, Packera glabella (formerly Senecio glabellus).  Yellow-top seeds germinate in late fall and winter.  By late winter, their habitat abounds in roseates of broad, dark green leaves with purple undersurfaces.  By February, flower stalks begin to rise to 12-24 inches and blossoming soon follows.

Since yellow-top flowering coincides with pollen production of oaks and pines, people frequently associate the showy flowers with hay fever.  Actually, yellow-top have relatively large, sticky pollen grains that are moved about by bees and other insects.  Oaks and pines, however, have wind blown pollen that, when inhaled, may cause illness.

The sheer beauty of acres of yellow-top is neat in itself, but the story doesn’t stop there.  We often forget that plants compete with one another, just as animals do, and they must also develop survival and reproductive strategies.  Yellow-top is very successful because it is one of the first bloomers, so when it is at its maximum growth and requires the largest amount of resources, there is little vegetative competition.  Also, since it is the first major bloomer after winter, it gets the bulk of attention from bee colonies that are beginning activity.  Judging from the density of stands of yellow-top, their niche seems to work.

Yellow top or butterweed, Packers glabella, in spring

But other than painting a yellow swath across the delta, does this glorious plant offer anything else?  It may well be the most economically important wildflower in Louisiana!  Yellow-top tends to grow in low, rather moist areas such as ditches, swamps, and back-water places along bayous and rivers.  Take, for example, the Atchafalaya River basin.  Each spring, yellow-top covers the exposed floor of the basin.  Before the river begins its annual rise, the bees visit and yellow-top completes its reproduction, sending its seeds flying into the breeze.  As the plants become covered by water, they die and decompose.  Enter the crawfish.  One of the most important functions of crawfish (off the platter, that is) is that they are detritivores, feeding mostly on nonliving organic material.  Crawfish spend their days chewing up their food source, changing big leaves and stalks into either small pieces that float away into the water or becoming crawfish edible tissue.  Yellow-top is the main entree on the menu, and without it our state would have a much smaller fishery of our Cajun’s “ecrevisse.”

                The next time you take notice of any of our natural resources, ask “I wonder how it fits into the overall scheme of things?”

THE UBIQUITOUS GENUS Phyllanthus

Sometimes it's just fun to put a name on something everybody has in their yard.  This is a quick discussion of Chamber Bitter (Phyllanthus urinaria) and Mascarene Islands Leaf Flower (Phyllanthus tenellus).

These plants are among the most common weeds in flower beds and yards in the Greater New Orleans region.  There is a tradeoff for their annoying abundance – they pull up by the roots very easily, and that is nice.

They are members of the Euphorbiaceae (spurge family), and neither are native to the U.S.  They are indeed common weeds, popping up in every nook and cranny from early spring to late fall.  As most weeds in our region, they persist through most mild winters.

There are about 600 species of Phyllanthus worldwide.  Some sources say there is no reported toxicity in these plants to humans, but Dr. Mark Plotkin, renowned ethnobotanist who is founding President of The Amazon Conservation Team and author of “Tales of a Shaman’s Apprentice,” says P. piscatorum is used by the Yanomamï Amerindian women for its piscicidal (fish killing) qualities.  Herbalists attribute many miracle remedies to other Phyllanthus species:  kidney and gallstones, jaundice, fever, headache, pinkeye, flu, dysentery, diabetes, gonorrhea, urinary tract and bladder infections, hepatitis B, and more.

Regarding our two local species, let’s define their parts.  They have a normally vertical stem to which leaves are attached.  A leaf is composed of a petiole (the central rib of the leaf) to which leaflets attach alternately (the bases not being exactly opposite the leaflet on the other side of the petiole).  This type of leaf is termed compound, and you have seen it commonly on legumes such as mimosa trees. For both species, the leaflets fold when touched (thigmonastic movement) and in response to light (nyctinastic movement).

They have flowers that ripen into fruits after being fertilized, and their placement on the petiole helps identify them to species as discussed below.  Both of these species have dense, but shallow, roots.

Because the species are very shade tolerant and produce copious numbers of seeds, they are perfect weeds.  Although they are annuals, their opportunities to often grow throughout the winter almost makes them perennials in New Orleans.

The species are easily distinguished.

My attention was originally drawn to this genus by Chamber Bitter.  Its scientific name, Phyllanthus urinaria, suggests that it has something to do with the urinary tract.  I have suffered several times from kidney stones, and anything that might alleviate that threat in the future instantly has my attention.

In the herbal world, this species is touted to treat and prevent kidney stones, the source of two of its popular names – shatterstone and stone breaker.  Googling it reveals sources of dried leaves that are taken as tea.  I do not recommend it at present, since I haven’t taken it myself.  But I’ve ordered some, and will be glad to share my experiences.

Chamber Bitter has dense leaflets that are wider near the tips than at the base and tend to overlap one another along their margins, giving it the appearance of a dense, soft little fern-like plant.  Their stems are often somewhat twisted and growing laterally along their lengths.  Its flowers and fruit line up below the green feather-like leaf petioles.

Chamber bitter, Phyllanthus uranaria, leaves.

Camber bitter, Phyllanthus urinaria, flowers and seed pods.  

Mascarene Islands Leaf Flower (so named after its Indian Ocean origin) has its leaflets more oval and smaller, thus rarely touching one another.  Their stems are erect and brown (red where the leaves touch the stem), and they bear their flowers and fruit on pedicels that extend above the leaves.

Mascarene Islands Leaf Flower, Phyllanthus tenellus.  Note the seed pods on
pedicels above the leaves.

As a believer in native herbal medicines, and a user of many, I have high hopes for relief from a very painful malady.  Stay tuned!

FOUCHETTE (BEGGARTICK SPECIES; NATIVE Bidens flowers - the yellow of our Fall

One of the world’s wonders is the annual phenology of nature. This is a fancy word that refers to the study of recurring cycles in nature.

Though I always enjoy adventures to the Barataria Unit of the Jean Lafitte National Historical Park and Preserve, I especially enjoy day trips in mid-October.

If I visit in the summer, I see largely green tangled masses of emergent and floating vegetation. When I return in October, I am likely to be greeted by a floral splay of radiant yellow, seemingly covering every open area in some parts of the marsh. This view is enhanced if there are white egrets feeding amongst the wetland plants – brilliant white splotches in a sea of resplendent yellow.

This dazzling yellow flower, in all its beauty, has the less than charming name of sticktight, or beggartick. There are actually two species, one is Bidens laevis – for sure abundant in the park - and the other has a much nicer name, Burr-marigold (Bidens cernua).

You know how we are in Louisiana. We have our own name – fouchette.

The two species are said to be easy to tell apart when they flower. Beggartick’s flowers stand straight up, and burr-marigold’s flowers droop down – they are nodding.  Many struggle discerning the two.

Next time you drive toward the river on I-310 in the fall, peek over the side as you drive and you may see a blanket of yellow caused by a multitude of Bidens flowers.

Bidens in flower in the swamp below I-310, October 2017.

There is a connection between nutria and fouchette. These flowers produce a seed that has barbed awns. Plants must have a system for distributing seeds, and fouchette disperses its seeds as “hitchhikers” when they stick on a passing animal and drop off somewhere else.

When the awns hook into the fur and skin of a passing nutria, they may create a tangled mess of hair and usually cause severe dermatitis, thus ruining the pelt’s economic value.

It is strange that in the days when the fur crop of America’s WETLAND was much more important, a plant that provides such floral beauty could have such a devastating effect on the economy!

BIDENS ALBA & BIDENS PILOSA.

When introducing these species to new naturalists, I comment on the difficulty of pronouncing and remembering scientific names.  I show them a specimen (usually of the more common Bidens alba) and say, “This should be easy for all of you, regardless of political persuasion.  It is commonly called “Bidens pilosa” - get it?  President Joe Biden and Congresslady Nancy Pelosi?  I always get lots of chuckles.

One of the most common roadside wildflowers (and a weed) is a Bidens species adorned with white ray flowers (which most people refer to as petals).  We actually have two species that to the novice appear identical:  Bidens alba and Bidens pilosa.  Here are their characteristics:

• Romerillo, Bidens alba - native to the U.S. - It is said that they have larger flowers with the ray flower more prominent.  The achenes (“seeds”) have two awns.
  
  
  Romerillo, Bidens alba flowers and 2 awned seeds.
  
• Shepherd’s needle, Bidens pilosa - introduced to the U.S., but native to Central and South America.  It is said that their white ray flowers are very small, sometimes hardly obvious, with the flower appearing more as yellow (the disk) with very small white ray flowers.  The achenes (“seeds”) have 3 or 4 awns.
  
  
   Bidens pilosa flower and 2-3 awned seeds.  From eBay.

In May 2024, I attended a gathering of that year’s Loyola graduates and their families.  Congresslady Pilosi was in attendance with her graduate grandson.  When it was pointed out that she was there, I ultimately decided I needed to tell her about my Bidens pilosa story.  She was surprised and amused, and we finished a polite discussion.  Later during the party she came over and informed me she had texted the President about our discussion.  Fun.

CRIMSONEYED ROSEMALLOW, Hibiscus moscheutos (widely known as the Wooly rosemallow, Hibiscus lasiocarpus)

One of the summer delights in Louisiana wetland habitats is the Crimsoneyed rosemallow, Hibiscus moscheutos ssp. lasiocarpus, a member of the Malvaceae.  Botanist now restrict Hibiscus lasiocarpus in Louisiana to the eastern side of the Sabine River; all others in the state are Hibiscus moscheutos - with some considering H. lasiocarpus as a subspecies of H. moscheutos.  Who knows what the interpretation will be when you read this!

Hibiscus moscheutus - a prolific summer bloomer.

Rosemallows are easily observed traveling across the LaBranche Wetlands, and along virtually all wet areas in America’s WETLAND (the Louisiana coastal area) where the salinity is not too high.

During most of the summer, they stand out from other plants due to their six inch wide flowers that have five petals ranging in color from white to pink. All are cup-shaped with a wine-colored center. Buds open in early morning, and the flowers fall off that evening.

The plant stands six feet tall, and grows back each year from its roots (it is a perennial).

Their stems branch from the base, may be reddish, and range from glaucous (waxy) and glabrous (smooth) to pubescent (covered with tiny “hairs” that are properly called trichomes).

Older leaves have several sharp tips, often with reddish veins, and look a bit like maple leaves.

Not only are wooly rose mallows beautiful plants, they are host and habitat to many interesting insects that inhabit the marshes and swamps.

If you have space in your garden for a glorious flowering plant that dies back during winter months, add the rosemallow to your botanic collection.

LOUISIANA’S NATIVE IRIS SPECIES

First irises have differences from other flowers:  See the image and definitions of their parts under “Flowers” above.

Spring is the season in south Louisiana to see irises of a variety of colors. Irises are aquatic plants that enjoy lots of sun and wet feet for much of the year. If you want to learn to identify irises and see a large variety of beautiful hybrid specimens, two events each spring will be a must for your edification:

1. Longue View Gardens hosts their annual Louisiana Iris Day in March or April (depending on iris flower development) for an  afternoon showing of their splendid iris gardens - all labeled, all native species on display, and many named hybrid species in full bloom.  There will be knowledgeable people to discuss the plants with you and usually nice violin music and wine.
2. The Greater New Orleans Iris Society will have a similar event with many gorgeous iris flowers around the same time in the iris gardens in the New Orleans City Park Sydney and Walda Bestoff Sculpture Gardens.

Irises seem to easily hybridize, and some that are now recognized as full species are of hybrid origin (e.g., the Abbeville Red Iris, Iris nelsonii, resulting from hybridization of Iris giganticaerulea and I. fulva).

Our native irises are blue or copper colored. If one encounters yellow, purple, white, or multi-colored irises, they are normally hybrid forms that were originally found in the wild around New Orleans and are now widely cultivated. But, I recently saw at the Louisiana Nature Center a cream-yellow flower on an Iris giganticaerulea that otherwise possessed the typical beautiful blue flowers of the species.

The following are our common native species.

Giant-blue (Swamp) Iris - Iris giganticaerulea - This is the tallest and bluest of our native irises. It is fond of swamps, though it will grow almost anywhere. The flowers are at or near the top of the plant, with no or very little length of leaves above them. The plants may grow to 5 or 6 feet tall.

Giant -blue (swamp) iris, Iris giganticaerulea, 
March 2017.

Zig-zag-stemmed Iris - Iris brevicaulis - The stems with flowers appear to zig-zag, i.e., not tall and straight. The flowers are lighter blue than the Giant-blue Iris, and the flowers are below the level of the tallest leaves. The leaves are about 2 feet tall.

Zig zag iris, Iris brevicaulis.  June 1988

Virginia or Southern-blue Flag - Iris virginica - The leaves are about 2 feet tall, and the light blue flowers that have a large yellow center are 3 feet tall.  The leaves are distinctive with a dark line (but not raised) down their center.

Virginia or southern-blue flag iris, Iris virginica. April 2015.

Copper Iris - Iris fulva - This species is easily identified since the flowers are a copper color. Though not seen very often, it may be locally abundant.  It occurs sporadically all across coastal Louisiana.  They may appear in virtually any freshwater habitat, but are very often seen in roadside ditches, around ponds, and in swamps.

Copper iris, Iris fulva, common, but rarely widely abundant in spring.

Abbeville red iris, Iris nelsonii (or, should it be Iris xnelsonii to indicate hybrid origin?) - The range of naturally occurring Abbeville reds is small, focused around Abbeville, Louisiana. They prefer swamps to ditches and lakes.  The petals range in color from red-purple to red or brownish.  There are occasional yellow flowers, but that variation seems to be found in all species.

Since they were named as a distinct species, some specialists have doubts that they are truly separate from Iris fulva, but they are still recognized as a full species.

The Yellow Flag - Iris pseudacorus - A  yellow flowered Old World species that has become commonly established in many areas in southern Louisiana. It has tall, broad leaves that stand 4-5 feet tall, and is easily identified by the presence of an obvious rib running down the center of each leaf. It has a series of dots arranged in a “v” on each petal.

Yellow flag iris, Iris pseudacora.  An introduced species that may replace native species.  
Note the raised rib that runs down the center of each  leaf.

Remember, if the flowers are purple, white, or other non-blue/non-copper colors, the plant is a Louisiana Iris of hybrid origin.

VERY IMPORTANT TO UNDERSTAND:  People refer to all irises found in our state as “Louisiana Irises.”  When early scientists/naturalists arrived they were treated to an array of multicolored iris patches.  No studies had been done, so they had to be very confusing to the discoverers.  

Since we now understand iris species that are native, there has been a tradition to call all those colorful hybrid plants as “Louisiana Iris.”  This is discussed in books on Louisiana iris species, and I think it is good nomenclature:  Louisiana native species (that have official scientific names) and “Louisiana iris” for hybrids that have no scientific name.

Let’s keep this tradition alive.

BALLOON VINE, Cardiospermum halicacabum

One of the most surprising discoveries when we research common local species is the high percentage that are non-native. Those that are difficult to manage and may cause harm to surrounding species are called invasives.

A somewhat common example is the Balloon Vine, Cardiospermum halicacabum (a really fun scientific name to pronounce phonetically), a genus and species belonging to the soapberry family (Sapindaceae) and described by Carolus Linnaeus. These common vines are native to the Old and New World tropics, escaping cultivation in the U.S. It occurs in the eastern U.S., and throughout Louisiana.

Seed-containing "balloons" of the balloon vine, Cardiospermum halicacibum.

The white flowers are tiny.  October 1985.

The common name derives from the seed bearing compartment looking somewhat like a Chinese lantern. The surface of the three-chambered balloon is papery. If squeezed, it will emit a popping sound and three seeds spill out. Each of the seeds have a whitish, heart-shaped marking, hence the generic name (Cardio = heart, sperma = seed). This also is the basis for another name for this plant – Love in a Puff (puff=the balloon; love=the hearts on the seeds).

The vines trail across the substrate, and usually climb over other vegetation using tendrils that are located in the proximity of the nondescript white flowers. The plant prefers open sunlight, and often spreads across grassy areas, with the seed pods looking very much like lanterns hanging about at a lawn party. Balloon vine seeds have been used for centuries by native cultures, especially in India and Africa, to treat skin itching and inflammation. It is the active ingredient in Florasone™, a natural alternative for cortisone creams.

PASSIONFLOWER, Passiflora sp.

Among the most beautiful flowers in the world are the passion flowers which bloom on a lattice-work of vines. The flowers range from pale nondescript tones to bright reds and the gorgeous regal coloration of our largest native species, the Purple Passionflower, Passiflora incarnata.

Two beautiful flowers of purple passionflower, Passiflora incarnata.

Passionflower vines are very aggressive, and once established, they may cover bushes and are very difficult to eradicate. That is their downside. Their upside includes the flower's beauty, and serving as the place where beautiful orange, black and silver Gulf Fritillary butterflies lay their eggs and their caterpillars feed. Once you have this plant established in your yard, you are guaranteed to have fritillaries constantly flitting about.

The purple flowers are three inches in diameter, showing a lovely, yet complex, architecture. In Christian lore, they have long been associated with the last days of Jesus Christ, thus the name passionflower. There are five blue sepals and five similarly colored petals, together representing 10 of the 12 apostles, excepting Peter and Judas who distanced themselves from Jesus just before the crucifixion. Two rings of thin filaments, representing the thorns on the crown, encircle the reproductive organs. The wounds on Christ's body are depicted by the five pollen-bearing stamens, and the three stigmas (the part of the pistil, or female anatomy of a flower, that receives the pollen) represent the nails in the cross. The tri-lobed leaves symbolize the spear that entered his flesh, and the tendrils that help the vines climb by growing rapidly and wrapping around branches portray the leather strips that cut his flesh.

The fruit of passionflowers are locally called maypops, thus the colloquial name for the flowers and plants, too. They may be eaten fresh, or used to flavor ice cream due to their sweet aroma.

Maypops are eaten by many.

Passionflowers have a symbiotic relationship with ants. They provide ants with nutritious nectar via structures called extrafloral nectaries (nectar sources outside the flower) - see the discussion of these structures above, located at the base of each leaf. In return, the ants protect the leaves from predators, including the fritillary caterpillars. Such activities are much more common in the tropics than locally. Some passionflower species actually have tiny structures that resemble butterfly eggs; they make gravid butterflies think that eggs are present, so they seek laying sites elsewhere.

Oh, yes. There is another local species that is not as showy as the purple passion flower. The yellow passionflower, Passiflora lutea, has yellowish-green parts of the flower and only slightly lobed leaves. It is quite common north of Lake Pontchartrain, but does not grab the attention that is common of its more elegant cousin. Close examination reveals, however, a stunningly beautiful cryptic twin of its more colorful cousin that is easily overlooked by those who are less observant.

Yellow passionflower, Passiflora lutea:  Characteristic leaf of the species and the pale green flower.

POISON IVY, POISON OAK, AND POISON SUMAC

People who knock around in the woods are aware of poison ivy, Toxicodendron radicans, but they often have problems correctly identifying the ubiquitous plant. They may know that it has three leaves, but I find they confuse it with everything from Virginia creeper, Parthenocissus quinquefolia, to peppervine, Nekemias (Ampelopsis) arborea.

Since plants that routinely cause dermatitis are abundant in our region, and because it is quite common for people to have strong reactions to them after brief contact, it is important for folks who enjoy the out-of-doors to recognize the big three:

1. Poison ivy, Toxicodendron radicans: A vine in our region (bushy in the north and northeast) that has leaflets in groups of three; the middle leaflet has notched margins and a rather pointed tip, and the other two leaflets have notched margins with one lobe a bit elongated near its base resembling a thumb sticking up from a hand. The vines typically climb trees and they produce small brown rootlets that grasp the tree’s bark. As the plant ages, the leaflets may become quite large and extend a considerable distance from the tree trunk, actually making the observer think they are the leaves of the tree. Although they drop their leaflets in winter, the leaflets may fall long after the tree leaves around them, so one may see an interesting leafed tree that, upon closer inspection, is a tree with a heavy growth of poison ivy. Since they most often climb trees, poison ivy plants are most often found in forest understories or along trails.

Poison ivy, Toxicodendron radicans - “3 leaves, let it be.”

Poison ivy vines always have thin, dark  roots for adhering to bark.

2. Poison oak, Toxicodendron quercifolia (you may see it as T. pubescens and possibly other names): This species grows upright, eventually as a bush (on the U.S. west coast it climbs trees like our poison ivy), may cover the ground, and has leaflets in groups of three, but with the “thumbs” referenced for poison ivy either absent or not as pronounced. Each leaflet is generally partially crenate (rounded toothed) and resembles certain oak leaves, hence the name. Young plants have very green, supple leaves; as they age, the leaflets stiffen and exhibit a yellowish color. Poison oak is more of a forest edge species.

It occurs north of Lake Pontchartrain, but has not been reported on the southern side.

Poison oak, Toxicodendron pubescens.

3. Poison sumac, T. vernix: This species has a shrubby growth form not unlike a holly or yaupon. The new stems and leaf rachises are red, and the leaves are pinnately compound. Each leaflet has smooth edges and a nice drip tip, and leaflets are opposite one another along the rachis. As they age, the red softens a bit, but retains those color qualities to a varying extent. They may easily be distinguished from real sumacs (genus Rhus) when reproductive by having green berries hanging down instead of the typical sumac berries that are red and stand upright. Poison sumac prefers moist areas, and is more common near swamps, lakes, and along seeps.

Poison sumac, Toxicodendron vernix.  Note the red stems.

Along our coast, poison ivy is the most abundant of the three species described above. The woods are full of it, and it is guaranteed to be present in public parks and will pop up in yards.

They all cause the same reaction, allergic contact dermatitis, and all have the same active ingredient, urushiol, an oily sap that is present in all parts of the plant. Some people are so sensitive to urushiol that slight contact causes dermatitis, even from dry plant parts. Exposure may happen by merely brushing against the plant, pulling up the plant while weeding, touching tools that have contacted the plant, or even petting a dog that has been running through the bush.

Seventy-five per cent of the human population has reactions to urushiol, and the extent of severity varies widely. Symptoms range from minor rashes, appearance of little bumps called papules, fluids oozing from irritated skin, or blistering. These may represent a progression of symptoms, or all may exist at the same time. Although all of these may be uncomfortable, they usually subside within days or weeks at most, with rare exceptions.

The most dangerous form of exposure comes with breathing smoke that contains urushiol. This should be considered a medical emergency, since mucous membranes in sinuses, the throat, and lungs are exposed and this situation can be life threatening.

It is commonly thought that the effects spread by contact with oozing fluids or rashes. Actually, it is only spread if urushiol on the sufferer is transmitted to others by touch. Some parts of the body may take longer to show signs after exposure, so one may think it is being spread from papules and blisters when it is really the urushiol still present on neighboring anatomy.

So, what are we to do, short of never entering the woods, parks, or our yards?

We should first take preventative steps:

1. Learn to recognize our poisonous species and stay on the lookout.
2. When in the woods, keep arms and legs covered and tuck pant bottoms in socks. Handle clothing with care when you return and wash them.
3. Remove urushiol plants from your property and have it removed from parks where practical.
4. Keep pets and other family from running the woods. A better idea is to encourage them to enjoy the out-of-doors and bathe them on their return.

What should you do if you come in contact with poisonous plants?

1. Wash exposed body parts with cool water and soap. Clean well, even under nails and your hair.
2. Clean any items that may have come in contact with the plants, such as tools, toys, etc.
3. Bathe exposed pets, kids, spouses, friends, etc.
4. VERY IMPORTANT: Go to a doctor if you have trouble breathing, you experience mucous membrane irritation, you breathe smoke, more than a quarter of the body shows symptoms, or there is infection.
5. If you have normal reactions (itching, papules, etc.), use calamine lotion or Tecnu (recommended by naturalist Irene Brady) liberally. Severe cases will require prescriptions.

Some people have reactions to plants that most of us consider innocuous. I have often heard of people getting itchy rashes after contact with trumpet creeper, Campsis radicans, but symptoms are said to be short-lived and this common vine has no effect on me. Plants like the aforementioned Virginia creeper contain oxalate crystals, but it is rare that someone has a reaction.

There are other plants in the U.S. that cause allergic contact dermatitis. Florida has Poisonwood, Metopium toxiferum, a relatively common species from the Caribbean rim. Although I don’t worry about the poisonous plants in coastal Louisiana, I am sensitive to poisonwood and often get rashes or blisters around my ankles when traipsing about in Belize. The good news about poisonwood is that it normally grows next to its natural antidote, gumbo limbo, Bursera simaruba. The fluid from boiled gumbo limbo bark poured over poisonwood rash results in rapid healing.

I wish we had such an antidote for our local poison plants. Well, we do, but most of us just don’t know enough about herbal healing. Two plants that can be crushed and rubbed on the Toxicodendron rash are jewelweed, Impatiens wallerana, and plantain, Plantago major. I’ll have to consult a local traiteur or one of my Native American friends to find local remedies.

MISTLETOE

The leafless winter season typically elevates one’s awareness of mistletoe. Our local species is Phoradendron tomentosum.

Mistletoe and Christmas have a long tradition that extends back to ancient civilization in Europe, with the Druids having many customs associated with their mistletoe species. Our mistletoe tradition is that one gets a kiss if one stands under the plant. It is common for people around the world to hang it in their homes, especially during the Christmas season.

The origin of the name appears to be from the Anglo-Saxon words “mistel” (meaning dung) and “tan” (meaning twig). It was called “misteltan” and was believed to magically emerge where birds’ droppings appear on limbs.

The entire plant is green and somewhat leathery, with tiny white hairs covering its leaves and its brittle stems. The plant anchors to a host plant and its roots invade the host.

Parasitic mistletoe plants may be abundant in woodlands, but disappear
into the foliage of trees.  Next  time you drive on interstates during the
heart of winter with leafless trees, you will see them everywhere.

True parasitism is a form of symbiosis in which one species benefits to the detriment of its host species. Mistletoe extracts water and minerals from its host, but it manufactures its own sugars via photosynthesis. Over infestation can kill the host plant, but that is rare. Usually mistletoe’s presence simply reduces the vitality of the host. This combination of partial parasitism and partial self-reliance makes mistletoe a hemiparasite.

Mistletoe flowers are not showy, and are found in the forks of the mistletoe’s branches. Its white fruits are drupes. Just like a peach, cherry or plum, the mistletoe drupe has an outer skin (the exocarp), a fleshy zone (mesocarp), and a hard container that contains the seed (endocarp). The endocarp protects the seed as it passes through a bird’s digestive system.

Birds, notably Cedar Waxwings, American Robins, Hermit Thrushes, and Eastern Bluebirds in our area, are known to eat the fruit. Birds are very important in distributing seeds of mistletoe by either anointing limbs with their seed bearing droppings or by wiping the sticky seeds onto a limb as they cleanse their beaks. This sticky material that surrounds the seeds, called viscin, hardens in the air and firmly attaches the seed to its new home.

It seems to be common knowledge that “mistletoe berries are poisonous to humans,” but they are not so dangerous to humans that we should be overly concerned.

Mistletoe juices of various types have long figured in biochemical research. Some interesting proteins, called phoratoxins, show promise as a possible treatment for such human maladies as breast cancer. A review of the medical literature suggests that mistletoe is emerging as something more than an excuse for a kiss.

DODDER, Cuscuta sp.

Next time you travel to Baton Rouge during the summer, keep your eyes peeled for what appears to be spaghetti growing on plants in the marsh. This tannish-yellow, pasta-looking stuff is dodder, Cuscuta sp. At least nine species occur in Louisiana, and about 150 worldwide. It is a member of the morning glory family (Convolvulaceae, though some specialists place it in the Cuscutaceae), and is a true obligate parasite (meaning that it must parasitize to live) on other plants. Dodder expert Dr. Colin Purrington, Swarthmore College, says, its "host is rarely killed, but always inconvenienced."

The parasitic dodder spreads over plants it finds delicious and taps into
their circulatory systems.

Dodder can be very dense

Among species of dodder in the United States, coloration ranges from yellow to bright orange depending on, among other things, the concentration of carotenoids. Being a near perfect parasite, dodder is virtually devoid of chlorophyll except in its fruit, stems and buds (dodder has no leaves).

Dodder is a flowering plant, with flowers white or tinged with pink or yellow.

The flowers are tiny, but pretty.  October 2014.

Seeds drop to the ground and germinate the following growing season if there are host plants in the vicinity. If there are none, seeds may go five years without germinating.

All curl (circumnutate) counterclockwise around stems of their host plants. The next logical question for the curious naturalist is if species in the southern hemisphere have clockwise circumnutation. Dr. Purrington says no, they twist counterclockwise in Australia, too.

Like vines on the rainforest floor, newly-germinated dodder vines have the ability to find even a distant host. Research shows that they find host plants by perceiving differences in light frequencies surrounding the potential hosts and sensing chemical cues resulting from volatile compounds emanating from nearby plants.

Climbing dodder vines are smooth surfaced. When they curl around a plant that is a good candidate for food, modified adventitious roots called haustoria, resembling prolegs of caterpillars (the leg-like appendages on the caterpillar's abdomen), penetrate the stem by a combination of brute force and the secretion of specialized enzymes that dissolve the cuticle of the plant.

Other than directly affecting the health of its host, dodder may also be a vector of phytoplasma (specialized bacteria that were once called mycoplasma-like organisms). Phytoplasma causes a plant disease called yellows, or yellowing, that has decimated the coconut population in the Caribbean and beyond. Sugarcane is also host to yellows (this is in addition to the sugarcane yellow leaf virus).

Dodder can be very intrusive, not only parasitizing plants that it consumes, but overwhelming other plants due to the expansiveness and density of its growth, strangling most along the way. Dodder can be controlled by a variety of herbicides, but one of the best control methods is to cut and destroy plants infested with dodder.

Enjoy viewing dodder during the summer, but know that it is basically up to no good and, in the grand scheme of things, we have yet to discover its virtues. Hmmm. Maybe if we start with a roux ...

WATER-SPIDER ORCHID, Habenaria repens

Our most common orchid is so non-descript and camouflaged in its aquatic habitat that it is seldom seen, even by avid naturalists.

The plant is the water-spider orchid, Habenaria repens. For years I've considered it a plant that thrives in acidic waters with loads of tannins, such as the lake at Percy Quin State Park in Mississippi. Although I've occasionally found it spottily distributed in Louisiana, I could always find it when my family spent time in Percy Quin. It ranges from Texas to North Carolina.

Habenaria repens - the flowers look like little spiders.

I was recently pleasantly surprised to find this orchid thriving in a small, yet very healthy, cypress swamp. It is abundant at the Jean Lafitte Nature Study Park, adjacent to Fisher Middle High School in the Town of Jean Lafitte, Louisiana.

This sensational nature area (replete with a 0.8 mile-long boardwalk) has cypress of all sizes, from seedlings to mature trees. Due to the presence of a thin canopy, the water surface sports a dense growth of many marsh plant species. In fact, the plants form a floating mat with the green water-spider orchids laced into the dense growth. You can easily follow the boardwalk and enjoy the cypress, heron rookery, the occasional alligator, and more, and not see the orchids at all.

The floating mat is perfect for water-spider orchids, because the species may set seeds and/or propagate by runners (stolons) that spread in all directions.

Water-spider orchids appear as one- to two-foot high stalks protruding from the surface. On close examination, the stalks are covered with greenish white orchid flowers that have the perianth (the sepals and petals together) divided into small elongated lobes that are reminiscent of spiders - thus the name. Their leaves are about ten inches long, and one inch wide.

See how Habernaria repens just blend into the vegetative surroundings  
Finding something like this results in a naturalist eye training venture!

In the evenings, the flowers emit a strong fragrance, which evidently attracts its pollinators - night-flying moths.

Habenariol is a chemical produced by water-spider orchids that deters feeding activities by red crawfish, Procambarus clarkii.

SWOLLEN BLADDERWORT, Utricularia inflata

Some plants just catch your attention. Such is the case with the swollen bladderwort (Utricularia inflata), Family Lentibulariaceae. It is a denizen of clear freshwater wetlands, but can survive in muddy situations if the water dries. Swollen bladderworts are native to the southeastern United States, but have been introduced to other parts of the United States where they are considered to be invasive species.

These insectivorous plants are virtually invisible to the untrained eye. The vegetative growth is entirely submerged and is a perennial that can become extremely dense, often resembling a thick hair-like mat just under the surface. They have no leaves, but do have filamentous branches off the growing stolons that are the main growth structures. Some botanists argue that these filaments are indeed leaves. Bladderwort do not have extensive root systems, but they may be somewhat loosely anchored.

Bladderworts capture their tiny invertebrates in the near spherical, one to three millimeter-long traps, or bladders (hence the name, bladder [traps] and wort [Middle English word for plant]). The traps are located in the axils of the branches. When prey touch the bladders, a trap door is triggered/sprung creating a vacuum that sucks the prey into the bladder.

The submerged elements of the plant have many bladders that,
when triggered, suck small prey inside for the plant’s nourishment.

Enzymes produced by the plant then digest the prey item. The most obvious part of bladderwort is the unique floral component. An inflorescence of up to 20 yellow flowers sits at the end of a stalk that extends about five inches above the water's surface.

When bladderwort is in full flower, one sees small yellow flowers randomly sticking out of the water, usually mixed with other aquatic species like water-shield (Brasenia schreberi) and fragrant water lily (Nymphaea odorata). Close inspection reveals that the flower stalks are supported by what is called a float consisting of four to 10 spongy spokes radiating from the base of the stalk. Each spoke of the float is branched and has bladders in and among the branches. The float with its flower develops underwater, and as the flower prepares to open, the float begins its ascent to the surface of the water. The flowers often open underwater and then emerge in full glory.

A Utricularia inflata flower afloat to the pollinated.  
Below it is the actual living plant that captures food
items from the water column.

Reproduction is by seed production and asexually by fragmentation of the vegetative portion of the plant. When their habitat dries, they may produce small tubers that allow them to survive until the water returns. Some say aquatic birds playing Johnny Appleseed with vegetative fragments often spread it. The bottom line is that this is one neat plant species that needs to be on your naturalist target list.

AMERICAN LOTUS, LOCALLY KNOWN AS GRAINE Á VOLER, Nelumbo lutea

From nanotechnology to good eats, our indigenous American lotus (Nelumbo lutea) is a fascinating and culturally important plant.  A member of the Nelumonaceae that occurs along sluggish waterways in most of the eastern United States, Central America, Colombia and the West Indies, it is also variously called water lotus, yellow lotus, water chinquapin, duck acorns (the seeds look like acorns sans their caps), pond nuts, and more.  In coastal Louisiana, we call them Cajun peanuts or graine à voler (gran ah vōlāy).

Lotus leaves floating on the surface (left),and some extending

above the surface while in flower (right).

Watch rainwater hitting the upper surfaces of lotus leaves and you will see it form droplets that may coalesce into puddles (the “lotus effect”).  The leaves repel water which beads up on the surface or fills the cup formed when the leaves extend above the water’s surface.  According to Casey LeBlanc, Des Allemands native who has grown up in the surrounding marshes and swamps, local fishermen use fresh rainfall caught by the lotus leaves as a safe source of drinking water.

Water being repelled by the lotus leaf, forming a puddle in the center.

The leaves have a waxy surface that slightly attracts water (forming progressively larger droplets) and nanoscale grooves and bumps that cause water to glide about on the leaf surface, thus cleaning the surface of the leaf of soil, bacteria and the like.  Nanotechnology involves discovering how things happen in nature at the nanometer scale (1 nanometer [nm] = 1 billionth of a meter) and duplicating those characteristics in human-made applications.  Scientists around the world are replicating the ultrastructure of lotus leaves and are applying the repellent system to a range of applications such as coating hulls of ships to protecting suspension cables.  Medical scientists are even using their knowledge of the lotus effect for diagnosing certain forms of cancer and creating vascular and bile duct stents that prevent fouling agents from adhering to their surfaces.  GE’s Global Research Center is experimenting with “hydrophobic nano-coating” paints for airplanes that may repel ice, thus eliminating the need to delay flights requiring the application of de-icing fluids.

Lotus leaves and flowers grow from rhizomes (laterally growing roots) anchored in the soil.  The leaves are perfectly round, smooth on top and ribbed on the lower surface, grow at the tip of a petiole (stem) that may be six feet long, and may float flat on the water surface or become cup-shaped as they extend into the air.  Their pleasantly fragrant white to pale yellow flowers are the largest native flower in the United States and they also grow at the tip of a stem that may be six feet long.

Lotus seed pods are cone-shaped with the seeds visible as bumps on the flat upper surface.  Oddly, they look like shower heads.  The pods are yellow when developing in the center of the flower, green when the petals and sepals fall, and brown as the pod dries and the seeds are dropped.  The spent pods are very popular in dry floral arrangements and are available in most flower shops.

Seed pod of Nelumbo lutea, which turns brown after seeds are dropped.

I have always heard that the seeds are shot out of the pods, thus the name graine à voler (flying seeds).  Indeed, when the seeds are ready to leave the pod, they become loose and rattle about in their cavities.  Joey Fonseca, another Des Allemands marsh expert, agrees that when the seeds are ready to drop, the pod dips over and the seeds simply fall into the water.

Native Americans seasonally relied on lotus in their diets.  They baked the rhizomes like sweet potatoes, steamed or boiled the unrolled new leaves, ate immature seeds raw, and roasted mature seeds or ground their contents into a starchy flower.  It is believed that the original distribution of American lotus in the United States was restricted to the area of today’s southeastern states.  The plants were probably transported north by Native Americans who either trekked south to harvest the plant or obtained it by trading.

Casey LeBlanc loves to pull over in his air boat, nibble on fresh Cajun peanuts, and soak in the ambiance provided by the surrounding natural wetlands and their inhabitants.  Like all good Louisianans, Casey has a number of recipes for graine à voler that are quite tasty.

Although American lotuses are fragrant, beautiful, and interesting components of our coastal freshwater wetlands, they often grow so thickly that they become a nuisance, unless you like to eat them!

DWARF PALMETTO, Sabal minor

The most visible indicator species of bottomland hardwood forests in south Louisiana is the understory-growing, shade-loving dwarf palmetto (Sabal minor). Although its densest growths are usually found in such habitats, it is often found spottily distributed along natural levees. They are distributed throughout the southeastern United States excepting most of peninsula Florida. In Louisiana, they are found statewide, but are most abundant in the southern half of the state.

The evergreen leaves of the dwarf palmetto are bluish-green and consist of an unarmed--meaning they have no thorn-like projections--leaf stalk (petiole) and a fan-shaped (costapalmate) assortment of about 20 long blades. The petioles may be up to three feet long; the fan ranges in size from one to five feet in diameter. Each of the blades has a central rib.

There are two growth forms of dwarf palmettos. The most widespread is called acaulescent--meaning the stem is completely underground--so the leaves appear to arise from the roots in the soil. This growth form is presumably an adaptation that protects them from fires in their habitat.

Sabal minor growth forms:  acaulescent (no trunk, left) and caulescent (with a trunk, right).

The other type is caulescent--or with a trunk. In the Bayou LaBranche area, there are trunked palmettos that reach heights of six feet or more. A specimen eight feet, eight inches tall was reported from Frenier Beach north of Bayou LaBranche's mouth on the west end of Lake Pontchartrain. Records of these plants in Brazoria County, Texas, reaching over 20 feet are now thought to be based on hybrid specimens.

The caulescent palmettos are possibly a growth response originating in specimens growing in crevasse zones along the Mississippi River. According to Tyrone Foreman, renowned local wetlands naturalist and Certified Louisiana Master Naturalist, the theory is that, as they were covered with alluvial soils as the river poured over their habitat, the stems continued to grow upward. Over time, the soil subsided around their bases leaving an exposed trunk. As they continued to add leaves (about three per year), they continued to grow higher ever so slowly.

This growth habit led Native Americans and early settlers to consider the habitat of this stalked form to be high ground--above the normal flood line.

The caulescent growth form was once considered to be the distinct species Sabal deeringiana. Today, we know it to be simply a growth form of Sabal minor.

Dwarf palmettos have clusters of small, monoecious (each having both male and female structures) white flowers on stalks that extend higher than the leaves. After flowering between late spring and midsummer, the ripening fruit are black, hard spheres less than one-half inch in diameter.

Black berries on Sabal minor.

In his 1945 Louisiana Trees and Shrubs, the late Dr. Clair Brown gives the following economic values for the species: roof thatching, source of fibers, and a producer of honey. We know that at least nine species of birds feed on their berries, as well as mammals such as opossums and raccoons.

The trunked form of palmettos take many years to grow, and they can be inadvertently killed in moments. Tyrone Foreman is deeply concerned that these wetland treasures will be killed by people who don't know their natural and scientific value. "Palmettos photosynthesize through their leaves. If they are cut for such purposes as basket making, thatching roofs, or building duck blinds, the result may be the death of a 250-year-old natural treasure," he says.

Foreman asserts that the national champion dwarf palmetto may well be standing in the LaBranche Wetlands. That would certainly be another natural feather in the cap of ecotourism for the Lake Pontchartrain Basin and Louisiana.

ELDERBERRY

Among the most conspicuous flowers of the season are the umbels of the elderberry (Sambucus niger - formerly S. canadensis). One of the most abundant local plant species, elderberries prefer open, well lighted places, although they will grow within woodlands. They are a common weed along urban thoroughfares and in backyards.

The plants are ubiquitous, spread like crazy, and are valued
vegetation in our ecosystem.

Elderberries have opposite branches and obvious lenticels.

Besides providing habitat for a variety of animals, elderberries are also important as their food source. Caterpillars and a host of other insects feed on their foliage, and all the local predatory insects may be found lurking in search of anything edible. If the insects are there, so are birds and lizards.

Elderberry berries, produced from early summer through fall, are extremely important for a host of local and migrating birds.

The leaves and stems are quite poisonous to humans. The flowers, however, may be dipped in batter and fried, and the berries are an excellent source for wine and jelly.  Elderberry syrup and pills can be purchased in most pharmacies.

Elderberries have also provided entertainment for children over the years. The trunks have a soft pithy core that can be removed to yield a hollow wooden tube. If another twig is whittled to fit snugly in the tube and a chinaberry or cork is wedged in the other end, a popgun results!

Note the pithy center of elderberries.

Old timers in south Louisiana made use of elderberry stems by removing the pith from a two inch section, drilling a hole near the base and inserting a hollow reed. Voila! A natural smoking pipe.

WAX MYRTLE, Morella (formerly Myrica) cerifera

The wax myrtle (Morella cerifera) is one of the most common shrubby trees in southern Louisiana. It has figured prominently in the development of our rich cultural heritage, and are now quite popular in landscaping throughout the region.

The leaves are very resinous and aromatic when crushed. The fruit of the wax myrtle are small wax coated berries growing along the stems. Forty species of birds, including the Yellow-rumped Warbler (formerly aptly named Myrtle Warbler), are known to feed on the fruit.

Biologically they are dioecious - meaning that male and female flowers are on separate plants.  If you wish to have them on your property to attract Yellow-rump warblers, you will have to plant females to get the berries and male to have them pollinate the females.

Morella cerifera wax-coated berries present in late summer and fall.

Wax myrtles, or bayberries as they are called up North (Alexandria and above!), were responsible for one of the first recorded local exports to Europe. Early wax-men, or ciriers, boiled the berries and stems, skimmed wax off the water, and produced bayberry candles. Favored for their aroma and persistence, this local product soon became popular throughout the Western World, especially among royalty. One must remember that before air conditioning and clean, running water, life could get pretty smelly, so people used many techniques to live well in their odoriferous surroundings. With the high demand for bayberry candles, wax myrtle was cultivated, thus becoming one of the earliest agricultural products of those arriving from Europe.

Another use of wax myrtle was even more creative and exists to this day. Blue crabs grow in size by shedding their hard outer shells. When freshly shed, their shells are soft and they are extremely vulnerable, so they seek shelter from predators. Early settlers (and locals today) took advantage of this by cutting the thick, shrubby growth-forms of wax myrtles and placing them in estuaries. Blue crabs that are about to shed crawl into safe places, like these branches, to avoid predation. Fishermen lift the trees out of the water and harvest the soft-shelled delicacies!

Wax myrtles are now extremely popular as landscaping shrubs, so our winter invasion of Yellow-rumped Warblers have plenty of places to dine.

BUTTONBUSH, Cephalanthus occidentalus

One of the most spectacular flowering plants in south Louisiana is the Buttonbush, Cephalanthus occidentalis.

Satellite plants, as I call them, have ping pong-size flowers that resemble the space modules. They are white and look a bit like spherical pin cushions due to their many styles (the projecting necks of their female structures), each tipped by a tiny yellow stigma (where the pollen is received).

Butonbush, Cephalanthus occidentalis, “satellite” flowers.

Buttobush being fed upon by bumblebees.

They flower constantly during the summer and are pollinated by a variety of bees, moths, and other insects. For such a delicate flower, they seem to be especially favored by large bumblebees.

Their branches splay beautifully, making them perfect habitat for spiders to build their webs.

Though buttonbush will grow on land (such as in my front yard), they are most often found in wet areas, ranging from roadside ditches to freshwater marshes and swamps. They are woody bushes that can grow to over ten feet in height, often with many sprawling branches.

The bark is susceptible to rot, but this doesn’t seem to be a detriment. It makes them a valued member of the wetland community, in that many insects have their larval development in their tissue, and birds such as yellow-bellied sapsuckers dig out nests in their trunks.

Leaves of buttonbush are dark green, have a leathery feel, and are regularly shed during the summer. They are deciduous, so they drop all their leaves in the fall.

Don’t delay. Visit the Barataria Unit of the Jean Lafitte National Park and see these beauties in full bloom.

PHYTOTELM - A SEA IN A TREE

Sometimes you just find good words that help you explain nature in the woods.  Fancy words are not required, but they are just fun and stimulate people to get into nature to find their newly learned target.

Phytotelm is just such a word.  A phytotelm is a hole in a plant that may or may not hold water.  A classic puddle observed on every walk in the local woods exists as a hole in a tree when a limb has fallen away.  The self-generated fluid in the modified leaves of Pitcher Plants (Sarracenia sp.) also form phytotelms, but we’ll discuss them at another time.

Phytotelm in a sycamore tree near the Coquille Trail at
Jean Lafitte National Park.

An entire ecological community can exist in these phytotelm habitats.  I've peaked in and seen frogs peering back, and it is not uncommon to find a sizable spider, especially the Dark Fishing Spider (Dolomedes tenebrosus).

What do you see in the phytotelm at the Coquille Trail?  
The answer is at the end of this account.

:

Several species of mosquitos use phytotelms, including the Yellowfever Mosquito (Aedes aegypti), Asian Tiger Mosquito (A. albopictus), and the Tree-hole Mosquito (Ochlerotatus triseriatus).        We have always feared that dengue (also known as “breakbone”) fever might reestablish in our area from the south, and the genus Aedes is a vector for the disease.  In order to better control these species, the New Orleans Mosquito Control Board some years back and under the directorship of Ed Bordes imported the large Elephant Mosquito (Toxorhynchites rutilus) from Hawaii.  The adults of this species are huge, maybe one inch in total length.  The adults do not need a protein boost to lay eggs, so they don’t bite humans.  The species gets its protein needs by, as larvae, eating other mosquito larvae sharing its habitat.  Since they love phytotelms and other standing water, they were considered good control agents for Aedes species.  Adults were released at night (if during the day, they were quickly snatched up by dragon flies).  The ones released did a good job, but the species never got established.  We do have a native species of the genus, but it doesn’t seem to do a superlative job as a pest control officer.

Of course, many species of invertebrates may seek refuge in phytotelms (millipedes, beetles, and the like) or breed in the water (such as midges).

On your next adventure into the woods, check out phytotelms.  But, don’t stick your finger inside or eyeball against the hole.  I’ve seen five foot long Western Ratsnakes (Pantherophis obsoletus, what we formerly called the Texas Ratsnake) disappearing into these openings, and a bite on the eyeball wouldn’t be venomous, but it would not be the best moment of your day!

What’s in the phytotelm?  A Carolina Wren used it for many nights.

TREE THROWS, OR, AS FOLKS IN NORTH LOUISIANA CALL THEM, HARRICANES

When walking the woods and swamps, one often finds where a tree has fallen over with the root system sticking into the air and a hole where the roots once resided.

This is called a tree throw.

The target of ecological studies, tree throws have yielded fascinating information, but in coastal Louisiana, they provide interesting habitats for the naturalist to explore.

Certified Master Naturalist Dave Dancer examines a
tree thow for hidden critters.

 Tree throws usually result in a bowl-shaped depression formed when the roots are ripped from their growth zone.  This may expose less weathered soils to the air, and over time the holes are filled in by sediment and organic matter.

They are havens for certain types of animals, and the fact that they may hold water when surrounding sites are drying makes them important to wildlife.  They provide drinking water, cooling pools, habitat for developing tadpoles and dragonflies, feeding and resting sites for snakes, and always, at some point, a wonderful growth zone for interesting plants.

Tree throws are prevalent along slopes in ravines and other steep zones, and are responsible for transport of soils down slope, making them a major factor in overall succession in many habitats.

In the spirit of thinking like a naturalist, when you encounter a tree fall, be sure to look around it to see if any critters are using it for hiding or feeding.  Make sure to note the direction the tree has fallen.  Are there other such falls in the vicinity?  Are they all lying at the same angle (this is why a good naturalist's tool is a compass or a compass app on a cell phone)?  Imagine what may have precipitated the event.  Any recent windstorms?  Could it be an artifact of an aging tree or forest?

If it is a recently created tree throw, an added interest should be that it may have unearthed artifacts from previous human activity in the area:  shards of pottery, bones, Civil War artifacts, trappers’ tools, or even some of Jean Lafitte’s long-lost treasures!

Although tree throws may appear anywhere, they are especially obvious in our area in swamps and older growth forests.  This makes them yet another reason to focus your natural history foray in healthy, aging woodlands, be they swamps or mesic forests.

THIGMOTROPISM

Thigmotropism is a concept in which living organisms move in a certain direction in response to touch (thigmo refers to touch; tropism to turn).

I was first exposed to thigmotrophy in a general botany class (thanks to the late and great Dr. Larry Erbe at the University of Louisiana at Lafayette, then the University of Southwestern Louisiana) when learning about how tendrils coil around a vertical support in order to climb.  I observe this phenomenon in my backyard each summer as I watch passion flower (Passiflora incarnata) vines climbing about.

For the moment, let us take a look at the most obvious thigmotropic response seen in New Orleans.  Have you noticed it when driving down St. Charles Avenue?

Next time you are on St. Charles Avenue, notice how the bases of many southern live oak trees (Quercus virginiana) seem to cover curbing at the edge of the street.  They appear to have melted and oozed along and over the upper surface of the curb.

Across from 7635 St. Charles, January 2020.

This is a thigmotropic response to the plant tissue touching the impenetrable surface of the concrete.

The first time I saw this response of a tree to a hard surface was in Arthur R. Marshall Loxahatchee National Wildlife Refuge in Palm Beach County, Florida.  Along the refuge’s fabulous swamp boardwalk, a number of bald cypress trees (Taxodium distichum) have similar associations in which they seem to flow over the boards, including handrails.  The refuge had a nice interpretive sign naming the process.  I took a couple of photos and stored the concept in the deep recesses of my brain.

One day, as I sat at a traffic light on St. Charles, I was surprised to see that our live oaks often have the same response.

Note as you look that many of the tree bases seem to end abruptly at the edge of the curb.  This may be due to several phenomena.  One is that maintenance folks may have used a chain saw or stump grinder to keep the tree from invading the surface of the street.  A second is that crews often cut the tree base and roots down about a foot below the street surface when building new or replacing old curbs.  A third way is that cars often sideswipe the trees and scar the bases by chipping off chunks of bark.

By the way, if you want to observe thigmotrophy on St. Charles Avenue, it is best to park and take a walk.  Otherwise, you are endangering yourself and others around you – no gawking and driving!

RED MAPLE, Acer rubrum - two varieties

Red Maple, Acer rubrum, is a native species that has crossed the horticultural line and become one of the most popular trees chosen for yards.  Their horticultural advantages are that they are fast growing and are deciduous, so the leaves give shade on hot summer days, yet allow warming sunlight through during cool winter periods.  Other wonderful features include their winter/early spring red flowers and buds, followed by showy red samaras, their winged “helicopter” seeds.  In fall, they are again showy when their leaves turn brilliant red to yellow, sometimes even orange, before they fall.  These make this species a much loved yard tree in the Greater New Orleans area.

Red maple, Acer rubrum, flowers are bright red and showing since

 there are no leaves on the tree.

Red maple, Acer rubrum, in flower along I-10 before other tree species in

February 2015.  

Red maple, Acer rubrum, samara seeds in February, often the tree is
loaded with the before any leaves are present.

Leaves begin to pop in March 2015.

Red Maple is arguably the most widely naturally distributed tree species in eastern North America, and this is due largely to it being a generalist – a very adaptable species.  It has many, many values in nature and beyond.  Many forms of wildlife feed and live on it, and hole-nesters love its cavities (the holes are called phytotelms).  Humans have discovered a wide array of uses for Red Maple, ranging from lumber to pulp to veneers to firewood, and much more.

Before we characterize the species, let’s visit the taxonomy of Red Maples.  When naturalists gather and Red Maples are encountered, someone will invariably mention Drummond’s Red Maple, Acer rubrum var. drummondii, and someone else will say that the varieties (including Common Red Maple, A. r. var. rubrum and Trident Red Maple, A. r. var. trilobum) are no longer taxonomically recognized.  In fact, they are valid, and being “varieties” they are not burdened with the reproductive requirements of species and subspecies.  In fact, all three occur in Louisiana, being found in the same regions but arguably separated by habitats.

We will focus on Drummond’s Red Maple, as it prefers wet areas (swamps) and is the one we encounter most often.

Drummond’s Red Maple has a leathery upper surface on its leaves, and a lighter lower surface.  This is evident when looking from the ground into a tree at night.  It differs from the other varieties by being pubescent (“hairy”) on the silvery lower surface of its leaves.  Leaves are opposite and have 3-5 relatively shallow lobes, with irregular tooth margins.  Petioles are normally red

Flowers appear in winter and are unisexual - female flowers are red and male flowers are red and yellow.  They tend to occupy different trees, but not always, as some trees have both male and female flowers present.

As mentioned above, the seeds are samaras, ranging in color from bright red to maroon, and make the tree very showy when laden with a large crop.  It is a thrill to be in the forest on a windy day when the samaras are falling.  They typically twirl about everywhere as they make their way to a potential germinating spot.

One of the thrills of driving down our highways in early spring is the normally continuous splashes of red caused by Red Maples being the predominant showy red vegetation.

CHINESE TALLOW

November and December are the months of amnesty in south Louisiana.  To be clear, my dislike for the most aggressive alien invader of our woodlands, Chinese tallow (Triadica sebifera, formerly called Sapium sebiferum), sometimes called chicken (they allegedly love tallow seeds) or popcorn (the white seeds look like popcorn) tree, transforms into a period of appreciation for the aesthetic beauty shown by the species’ broad spectrum of colors in its fall foliage.

Chinese tallow is so named because it was introduced from China to the United States in Charleston, South Carolina, in the late eighteenth century by the French botanist Francois Michaux, although Ben Franklin frequently gets "credit," or is it blame?  The original intent of its introduction was to develop a soap industry based on the wax coating of the white seeds.

In early spring, tallows produce catkins, or aments, that contain both male and female flowers.  They smell very sweet, and are popular with bees, producing a very tasty honey.

Chinese tallow catkins.

Tallows are extremely genetically variable.  Have you noticed that some tallow trees lose their leaves while others retain them?  Some turn red, maroon and yellow while others remain green?  Some have ripe seeds while others don't?  This extreme variability allows propagators to select trees with certain characteristics, such as amount of wax on the seeds, that are deemed desirable and, by artificially crossing them or collecting and planting their seeds, expand the presence of those characteristics in the orchard

The long summer provides for nice, green flowers.

 Many leaves turn yellow and orange into the fall, and the ripe, white seeds are obvious.

Many tallow trees drop all their leaves while retaining ripe seeds

Even though seed production once reached 10,000 pounds per acre, the tallow orchard venture failed because harvest by hand was not cost effective.  The abandoned orchards spread quickly and the tallow is now one of the most abundant trees along the Gulf and U.S. south Atlantic coasts.  Birds eating and eliminating their seeds facilitated the rapid dispersal.  Additionally, people frequently chip them and use the chips to cover walkways and trails, a big mistake since this is a human way to introduce seeds to new areas.  Their ultimate success is due to the same features that unfortunately endear tallows to the hearts of new homeowners in the New Orleans area, especially their tolerance of poor soils and rapid growth.  Yes, Chinese tallows are sold in virtually all local nurseries, and people buy them!

The trees will grow virtually anywhere and may reach 40 feet tall within 10 years.  They are, however, quite messy, constantly dropping limbs, and short-lived (about 40 years).  Tallows are herba non grata in most natural places since they grow much more rapidly than our native trees and thus out-compete and rapidly replace them.

November-to-December, as mentioned, is a period of brief truce between tallows and many naturalists due to the trees’ lovely yellow, red, and maroon leaves mixed with the brilliant white seeds which resemble popcorn and provide low preference food for birds.   Some call it the Cajun New England.

Tallows have also been planted to stabilize banks in rapidly eroding wetlands.  They proved to be hardy in these environs and their roots hold the soil together.

Nevertheless, the leaves soon fall and the battle wages on.  Tallows are very difficult to eliminate due to rapid growth of shoots from stumps.  Once established in a woodland, they are virtually impossible to remove.  As a wise old Cajun once said, "You don't kill tallows, you just make them mad!"

Tallows need to go!

SUGARBERRY, OR SOUTHERN HACKBERRY, Celtis laevigata

Many people consider sugarberry trees (Celtis laevigata) to be an unattractive nuisance. Though they may not be one of our most sought after ornamental species, they play an important role in nature.

Hackberries are fast growing, yet short-lived. They may grow to 20 or 30 feet tall in just a few years, but groves begin to die out between 40 and 70 years later. This is not a good trait if one wishes to line the entrance to the family plantation, but it is nice if you have built a new home on a shade-less lot.

As limbs fall and the weak trunks split with age and disease, cavities are formed that provide wonderful habitat for a variety of wildlife and other forms of life such as fungi and a host of insects. The nut-like fruit of sugarberries is a wonderful wildlife attractant. During the winter, these trees are a favorite for flocks of Cedar Waxwings, one of our most beautiful birds.

One of the most unique features of sugarberries is the spongy, warty outgrowth of the bark. They grow in conjunction with the tree’s lenticels, tiny pores that allow for air exchange in the bark. This very rough texture gives the trees an intriguing appearance and provides a myriad of nooks and crannies for tiny critters to live.

The characteristic bark ornamentation of Sugarberries, with variation from almost
smooth to bark like this photo.

These trees produce copious amounts of seeds that are preferred by many local birds.

It is not uncommon to find dense stands of sugarberry in the Mississippi River Delta. They do quite well in alkaline soils and seem to be unaffected by alternating periods of drought and deluge. During plant succession, the gradual replacement of one plant community by another over time, a hackberry dominated forest appears to precede the final step in the delta region - live oaks.

The Audubon Louisiana Nature Center’s forest is a good example of this sugarberry transition (called a “seral stage”). Before 1914, the site where ALNC is located was a brackish marsh. It was drained to make way for future development and plant succession began. Marsh vegetation gave way to a wave of new plant invasions, each changing the soil as it went through its life processes and unknowingly preparing it so that yet other species could grow and prosper. After a number of years, hackberries gained a foot-hold. They gradually became more numerous, displacing other species. Before Katrina, some 91 years later, the forest was 90% sugarberry and 10% a mixture of live oak, elm, maple, and many understory plants. The oak trees were rather stunted, stretching for light above the hackberry canopy. As sugarberries fell, more light hit the ground and the oaks began to expand their growth.

ALNC sugarberries were suffering from two major afflictions. They were susceptible to a root fungus (Brittle Cinder, Kretzschmaria deusta) that appeared around the base of the tree as a black, crusty growth. This fungus didn”t appear to interfere with normal life processes and, other than the fungal growth, the trees appeared healthy. However, the fungus weakened the roots and, following a wind storm, the tree may be found toppled over. Inspection of the root-base revealed a break between roots and trunk that was so clean that it appeared to have been done with a chain-saw!

The other problem faced by local sugarberries is infestation by Jumping Plant Lice. These are tiny leaf-hoppers that suck the juices from the leaves. Healthy trees can support a thriving colony of these insects, but over-infestation will lead to yellowing leaves, defoliation, and often the death of whole limbs of leaves. The plant lice look like miniature cicadas, having a total length of about a tenth of an inch. Their most obvious sign is the presence of tiny white circular shields on the under-surface of leaves. These are produced when the larvae pupate, thus undergoing changes that result in the adult stage. When infestations are high, vast numbers of these “scales” may accumulate under sugarberries as the plant lice metamorphose en masse. Some locals call these piles of white flakes “summer snow.”

MARDI GRAS TREES COME INTO FULL BLOOM AS THE SEASON PROGRESSES

As we approach Shrove Tuesday in New Orleans,  Mardi Gras trees (Arbor carnivalense) suddenly burst into full bloom, becoming festooned with bright colors that sparkle in the sunlight.

This species seems to occur predominantly along parade routes (or, do we route our parades along streets lined with this species?), but the blooms and fruits make their way down side streets, and people adorn themselves with them as well.

Some blooms/fruit are caught on fences and gates around houses, and some seem to wrap around signs or telephone posts.  Observation suggests that many may be distributed by humans when they land around their necks.  Many are removed in bags and boxes.

Are the bright colors of the blooms/fruit a superb enticement for humans to gather them and distribute them?

Every New Orleanian knows that the proper destination of such blooms/fruit, at least in the short term, is storage in their attics until removed the following year for sharing and redistribution.  An increasing number of people make sure they are given to organizations such as ARC of New Orleans and St. Michael Special School where they are lovingly repackaged and made available for another year.

Trees along the parade paths gradually have more and more blooms and fruits (beads).  Following the Tucks Parade many of the trees are covered with long white streamers that are very light and dance in the breeze.  Are these similar to dandelion seeds whose design allows for wind dispersal?  If the beads are the blooms or fruit, are these streamers resembling toilet paper the seeds being distributed for next years’ events?

And what about those glittered shoes that appear after Muses?  If the blooms and fruit fall to the ground, do shoes they contact magically become sparkled with an array of glitter colors?

So many unanswered questions!  You are urged to “think like a naturalist” and help us understand this annual occurrence.

LAGNIAPPE:  Have you noticed strange tracks along parade routes?  Long overlapping “stripes” on the roadways are made by rolling medal rimmed wooden spoked wheels from traditional parades such as Rex.  Odd golden semicircles are left on roadways when riding lieutenants of Krewe d’Etat spray paint their horses’ hooves.  What else have you noticed?

NATIVE MILKWEEDS

Read the following discussion of today's suggestios about the past popular planting of non-native Mexican milkweed, Aesclepias curassivica, and why we have an evolving set of improving recommendations.

Migrating monarch butterflies lay eggs on native milkweeds on which the larvae can feed.  Across the nation there has been a massive reduction in densities of native milkweeds, mostly due to large-scale agriculture.

The presence of wild native milkweed is important in the normal migration movements of butterflies and serve the insects well.  The monarchs have evolved with their availability over time and these are present during population movements. Using the readily available Mexican milkweed, making it abundantly obvious for prolonged periods, plays havoc with normal movement patterns causing two major challenges discussed below:  1) holding them in place in American instead of them moving on to their natural winter grounds in Mexico, and 2) causing an increase in the presence of the “Oe” protozoan parasite (Ophryocystic elektroscirrha) discussed below.

Here are a couple of species that you might find in the wild in the Greater New Orleans region:

Aquatic milkweed, Asclepias perennis a very short bushy species.

Longleaf milkweed, Asclepias longifolia, a vine easily overlooked if not in flower.

2025 INTERPRETATION OF MILKWEEDS AND MONARCH BUTTERFLIES.  

Well-intentioned Human Intervention: Does planting non-native milkweed actually help Monarch Butterflies?   By Linda Barber Auld, NOLA BugLady and Ginna Hoff

In 2013 it was shocking to hear the reports from the national organization Monarch Watch about the lowest overwintering monarch butterfly population in recorded history. Believing it to be helpful, we gardeners rushed to our local garden centers, and purchased the milkweed on the shelves. Unfortunately, at that time, native milkweeds were not being produced for many retail markets therefore only non-native “Scarlet”, “Silky Gold”, and “Giant” were readily available. Yes, they are beautiful plants, and monarch caterpillars will eat them, but did this actually help? What is the difference and why does it matter?

Mild winters without freezes allow tropical milkweed to survive from fall into the following spring. Areas north of Lake Pontchartrain experience much colder winter temperatures that cause natural tropical milkweed die-back. (After spring bloom time, wild native milkweeds growing through their instinctive cycle will die back.)  The Oe protozoan parasite (Ophryocystic elektroscirrha) is known to be a debilitating and sometimes lethal disease endangering monarchs. Oe is exceptionally rampant in warm winter locations where non-native milkweed is abundant and infects caterpillars that eat spores on milkweed leaves. These leaves accumulate spores environmentally and particularly from spore-carrying females during egg laying. From a variety of sources, specific protocols for controlling Oe by managing milkweed are available and being used in locations such as New Orleans, where Oe infection incidence in fall measure 90-100%. Years of intensive studies of metro New Orleans conducted by Tulane University students confirmed the following results:

1)        Monarch caterpillars that ate tropical milkweed develop smaller wings, hindering them from long-distance migration and creating a large non-migratory population.

2)        The quick regeneration of non-native tropical milkweed leaves enables monarchs to repeatedly use the same plant, only helping Oe to thrive.

3)        Overcrowding caterpillars on milkweed is a known major condition that spreads Oe infection spiking in summer and fall in Southeast areas.

4)        The winter breeding population is heavily infected with Oe and likely to contaminate habitats that migrants from all migratory populations encounter.

5)        New Orleans area gardeners should supply milkweed only in spring for healthy monarch migrants and thereafter, provide blooming nectar plants.

6)        This is why we cut back “used milkweed” beginning June 1 and repeated after each “wave” of caterpillars.

We know that New Orleans, Houston, and parts of the Florida peninsula are breeding infected monarchs (University of Georgia website: monarchparasites.org/maps).

But what about other areas along the Gulf Coast?  The greater Gulf Coast shoreline area has long been a spring east-bound flyway for monarchs migrating to the USA from Mexico.  In Pass Christian, Bay St. Louis, Ocean Springs, Mobile, and D’Iberville, concerned citizens have been creating pollinator habitats to support butterflies including migratory monarchs. In 2023, volunteers in these cities were trained to sample for Oe presence. The data created from this citizen science project proved that all across the shores of the Gulf of Mexico this parasite mirrored very similarly high fluctuating levels. Hopefully this research will help us to better educate those who are interested in Oe and milkweed management.

RAGWEED (SNEEZEWEED), Ambrosia sp.

You know that a plant must have some interesting qualities if it only grows in disturbed areas. Such is the case with ragweed, a plant that connotes a drippy nose and runny eyes for many.

A wry sense of humor led to ragweed being given the generic name Ambrosia, meaning “food of the gods.” Its rough surfaced leaves are regularly eaten only by insects, though horses and cows will consume them if other food is scarce.

Two species abound in south Louisiana. Giant ragweed (Ambrosia trifida) may be l0 feet tall with large deeply lobed leaves. Common, or dwarf, ragweed (A. artemisifolia) is shorter, usually four feet tall, and has delicately dissected leaves. The flowers of both are in the junction between leaves and stems while the pollen is produced in upside-down cup-like structures lining the branches. Ragweed pollen is distributed by the wind and is a primary cause of allergies during the fall.

Giant ragweed, Ambrosia trifida, plants, leaves, and pollen-laden staminate flowers. September.

Leaves of Common or dwarf ragweed, Ambrosia artemisifolia.

Ragweed is truly a pioneer species, normally being one of the first to invade barren soils. It is a very important element in our ecosystem in that it produces nutrients that further enrich its soil, thus paving the way for the invasion of other species having different ecological requirements. This phenomenon is known as plant succession.

These plants are fall bloomers, and they reproduce by spreading huge amounts of small pollen with the winds.  This is happening when goldenrods (Solidago) are in resplendent flower - very dense stands and right yellow in color.  Pollen sensitive humans see the goldenrods and are sneezing - blaming them for their allergic reactions.  In reality, goldenrods are largely pollinated by wasps and bees.  Their pollen is relatively large and sticky, so they don’t travel through the air.  Remember the old science adage:  Correlation is not Causation.  When we start sneezing and we see all those bright yellow flowers, we blame goldenrods, which are blooming at the same time (correlation) as ragweed (which is making us sneeze) so we naturally think we sneeze due to goldenrods because we don’t see the pollen of ragweed.  I tell naturalists the only way you will sneeze from goldenrods is if you stuff your nose with their pollen - but if you do, the only thing you will have is a plugged nostril!!!

Another curious characteristic of ragweeds accelerates their eventual disappearance. As they grow, some roots die as new ones develop. These decaying roots release a toxin that is harmful only to ragweed. When concentrations are high enough, the soil can no longer support these invaders and they die, thus paving the way for new species of plants to replace them.  Is this true altruistic “behavior?”

So, if you are allergic to ragweed pollen, have patience. This, too, shall pass!

TORPEDO GRASS, Panicum repens:  TOLERANCE DOESN'T COME EASY.

“What is the deal with torpedo grass?  It is taking over my neighborhood and we are desperate to know how to control it,” asks Ron Glancy.  A resident of the West Bank of Greater New Orleans, Ron finds lots of invasive life and shares his discoveries.

Torpedo grass, Panicum repens, typical growth.

Torpedo grass, Panicum repens, showing dense growth in Metairie yard.

Well, there are no happy solutions to the torpedo grass invasion, reports Andrew Loyd, local LSU AgCenter Extension Agent.  He says, "You can't control it, you can only manage it."

The species, Panicum repens, was introduced to the United States from Asia in 1920 by the U.S. Department of Agriculture.  Its intended purpose was to provide a new forage crop for cattle.  Cows do eat it, but it has very low nutritional value to them, and it is toxic to horses.

It does well along the Gulf coast, and is known from northern Louisiana and Mississippi, as well as Arkansas, but cool temperatures give it grief, so it can’t spread much farther north.

Although it does produce seed, in the U.S. these seeds are infertile and do not contribute to the dispersal of the species.  It is unfortunate, however, that it spreads vigorously vegetatively – from parts of its root system being moved around.  Once established it is akin to Attila the Hun as it marauds nature by rapidly growing stolons that run a foot or so beneath the surface in all directions.  One day you don't have it in your yard, and the next it is popping up everywhere.

So how does it arrive at your abode?  The most widespread way is if you buy river sand, especially originating from the Bonnet Carré spillway.  Torpedo grass is abundant there.  It can, however, come from other sources in and around the city.  If buying soil, one should always ask if it is “torpedo grass free.”  If they guarantee it, it probably is.  If they equivocate, beware!

And why be so cautious?  Because once you have it, it is near impossible to eliminate.  Dr. Ron Strahan, torpedo grass research leader with the LSU AgCenter Extension Service, says the only option that normally works is to completely dig up your yard, down several feet, and replace the soil with uncontaminated soil - a very expensive and labor intensive endeavor, indeed.  Even then, Strahan says, you run the very real risk of the species reinvading your property from a neighbor’s yard.  If it is nearby, it will be back!

Dr. Strahan stated that there are no chemical controls that work on torpedo grass in our most popular lawn turf, St. Augustine.  Any herbicide containing sethoxydim will suppress it temporarily, but it will probably survive.  An option is to replace the St. Augustine with either zoysia grass (if shade is present) or Bermuda grass in sunny areas.  If you choose this route, you will have to often treat your yard using the herbicide "Drive" (containing the active ingredient quinclorac).  Drive will keep torpedo grass from dominating, but its application will be an ongoing activity.

Grant Estrade, of Laughing Buddha Nursery and Wood Materials, says the best controls include creating shady spaces. Torpedo grass doesn't do well in the shade, so it is at least somewhat suppressed.  Under bushes in the sun, it will grow very tall, and extend above the leaves on the bushes, such as azaleas.

Torpedo grass seems to have no controls anywhere in our environment.  It even tolerates salt, and grows on barrier islands.  We don’t think that even nutria will eat it!

Our neighbors to the north may not continue to escape this challenging grass.  Biologists who study the ecology of plants and animals have for years reported changes in the phenology (relationship of temperature and other environmental factors to activity) of their research subjects.  They have noted that over the years, there are signs that spring weather is arriving earlier in increasingly northern latitudes – frogs are calling earlier, flowers are blooming sooner, salamanders are mating days or weeks before established norms.  All these ecological signals are being interpreted as subtle adjustments due to climate change.  Will torpedo grass begin to expand its range northward?  Nothing is suggesting otherwise.

Sorry, Ron - wish I could be more encouraging.  Sometimes invasive species just win!

SEA OATS, Uniola paniculata

Sea oats (Uniola paniculata) is a beautiful grass species with tall, golden seed heads that are characteristic of sand dunes along the Gulf and Atlantic coasts. They are among our most important coastal plants in that they grow along sandy beaches where they stop blowing sand grains, thus contributing to the building of sand dunes.

They are rare west of the Mississippi River.  They are established and spreading on Elmer’s Island, and were planted there purposely to protect the dunes.  Next time you go to the panhandle of Florida, see them flourishing in their native habitat.

Sea oats, Uniola paniculata, Elmer’s Island, July 2014.

As one might expect, sea oats are very tolerant of salt spray and rather high salt content in the soil. Research suggests that salt spray is the principal source of nutrients in an otherwise relatively nutrient deficient world of beach sand.

Sea oats spread asexually via rhizomes, basically underground stems that occasionally produce a new plant before continuing on. They may reproduce sexually, being fertilized by wind blown pollen. The seeds are produced from spring to fall and are mostly wind distributed, but may also float in surface waters.

They are one of the few plants that can grow upward as their bases are covered with soil. This allows sea oats to lay down dense root mats that help build the dunes, and keep growing up to maintain themselves and continue capturing blowing sand grains.

Seed eating critters such as a variety of birds, mice, rabbits, and their friends feed on sea oat seeds.

Research has shown that they are clearly the most effective sand dune builders in the area. For this reason, they have government protection due to their value in stabilizing beaches. One should never dig or cut sea oat plants, nor take their attractive seed heads to use as ornaments. Doing so threatens the viability of the sand dune community, and subjects you to fines and possible imprisonment.

SHORELINE SEDGE, Carex hyalinolepis

Something that all naturalists experience is finding a species that they don't know.  For the average person, it is impossible to know all of nature, and my challenge, and one of my loves, is plants.

I've walked the boardwalk at Turtle Cove Environmental Research Station, Southeastern Louisiana University's facility on Main Pass near Manchac, many times.

When there recently with a Louisiana Master Naturalist class, I found a wetland plant in great abundance along the walk.  I had never noticed it before, and that only means just that - that I had never noticed it before.  It has probably always been there but I looked right past it while looking for other local species.

I guessed that it was a member of the genus Carex, a genus of sedge (Family Cyperaceae) that has over 2000 species and a global distribution.  I had no idea what species it was, nor did I feel proficient in identifying the species that are commonly encountered.  I sufficed to walk by them and say, "This is Carex."

Shoreline sedge, Carex hyalinolepis, as the seed heads develop.  Turtle Cove Environmental Research Station.  March 2014.

Shoreline sedge, Carex hyalinolepis, mature seed head  Turtle Cove Environmental Research Station.  February 2019.

I took photos and examined specimens closely.  When I got home, I did what I often do when I have unidentified plants, I send the photos or samples to an expert.  This time I went to Dr. Mac Alford, the gentleman botanist from the University of Southern Mississippi.  Mac normally knows everything I send, but this time he referred me to his expert - Dr. Charles Bryson of Starkville, MS.  I knew I'd found the right person when his username is dr.sedge@.

Dr. Bryson responded immediately with the identification - shoreline sedge, Carex hyalinolepis.  For many, that is enough information, but naturalists like to know how newly recognized species fit in the natural scheme of things.

Of course, shoreline sedge growth functions as habitat and a hiding place for many critters that live in the area.  I was also informed that shoreline sedge is the main (possibly the only) food for the rare Dukes skipper butterfly, Euphyes dukesi.  If one finds shoreline sedge, Dukes skippers are not far away.

Duke’s skipper,  Euphyes dukesi.

By the way, saying “skipper butterfly” is permissible, but is a bit redundant.  Skippers are butterflies that belong to the Family Hesperiidae.

The seed heads of Carex are often football-shaped with a rough surface.  When in flower, they have male (=staminate) spikes that are the terminal dark brown spikes and below are the green female spikes, the perigynia, little sacs that contain first the female flower, followed by the fruit.

It is the rugged nature of the female spikes that cause me to call out Carex when I see it.

The next time you see an abundant non-descript plant, you should wonder who depends on it - connecting the dots, so-to-speak.

THE AKERS (MANCHAC) ENT

A boat adventure through the homes on the Galva Canal in Akers (Manchac), Louisiana, reveals the presence of an ENT.  We’ve never seen it move about or talk to us, but keep your eyes open.

November 2017.