CLASS: XI
MORPHOLOGY OF FLOWERING PLANTS
RAVI A, PGT BIOLOGY
JAWAHAR NAVODAYA VIDYALAYA BALEHONNUR
CHIKKAMAGALUR DIST., KARNATAKA - 577112
MORPHOLOGY OF FLOWERING PLANTS
Morphology is the study of size, shape and structure of plants, animals and microorganisms and of the relationship of their constituent parts.
Radicle - It is the embryonic part which gives rise to the Root system
Plumule - It is the embryonic part which gives rise to the Shoot system
PARTS OF A FLOWERING PLANT
A typical flowering plant consists of
b) an above ground shoot system
ROOT SYSTEM
The radicle of the embryo of seed gives rise to root system
General characteristics of Roots
(i) Roots show no nodes and internodes
(ii) They do not bear any bud
(iii) They are positively geotropic & negatively phototrophic
(iv) The roots are normally underground & non green
Functions of Root system
(i) Roots anchor the plant to the soil
(ii) They absorbs water & minerals from the soil
(iii) The root tip synthesize plant growth regulates
CLASSIFICATION OF ROOT SYSTEM
Root system | ||
Tap root system | Fibrous root system | Adventitious root system |
Here the radicle continues to grow as primary root & gives off branches of various orders forming a tap root system It is characteristic of dicot plants | When the radicle is repeatedly branched & forms a tuft of roots from the base of the stem, it is fibrous root system It is characteristic of grasses like wheat (Monocot plants) | When roots arise from any part of the other than radicle, they are called adventitious roots. |
REGIONS OF THE ROOT
● Tender root apex is protected by thimble like structure called root cap.
● Just above the root cap, extending to a few mm above is the meristematic region.
● The region of elongation lies proximal to the meristematic region.
● The region of maturation lies just above the region of elongation
● A cluster of root hair arises from the epidermal cells of the region of maturation.
MODIFICATIONS OF ROOT
When roots change their shape & structure to perform functions other than anchorage & absorption they are called modified roots.
(i) Storage roots
Tap root modification
(Eg: Carrot, Turnip, Radish etc)
become swollen with stored food materials
Adventitious roots
(Eg : Asparagus, sweet potato etc)
become swollen with stored food materials
MODIFICATIONS OF ROOT
(ii) prop roots
Prop roots are massive pillar like out growths of aerial branches, which grow downwards & become large & woody, to support the expanding canopy of the tree.
Eg : Banian
(iii) stilt roots :
These are supporting roots which arise from the basal nodes just above just above the ground.
Eg : Pandanus, Maize, sugar cane etc.,
(iv) Pneumatophores :
These are the branches of roots that grow vertically above the ground & bear openings called pneumathodes for exchange of gases. These are found in plants like Rhizophores, Which grow in marshy areas.
SHOOT SYSTEM
It develops from plumule of the embryo of the seed
General characteristics of stem
(i) Nodes and inter nodes
(ii) bear auxillary & terminal buds
(iii) generally green when young & later became woody & dark brown
Functions of stem
(i) Spreading out the branches, bears leaves, flowers & fruits
(ii) It conducts water & minerals absorbed by roots to the leaves & the organic food prepared by leaves to roots & storage organ.
(iii) Stem becames modified for perennation (is ability of organism particularly plants, to survive from one germination season to another especially under unfavorable conditions such as drought or winter). Vegetative propagation, protection, support & Photosynthesis
MODIFICATION OF STEM
MODIFICATIONS OF STEM
(ii) TENDRILS – Tendrils are slender & spirally coiled structures that help the weak stemmed plants to climb on to support.
Eg : Cucumber, Grapevine etc.,
(iii) THORNS – Thorns are woody, straight, pointed structures, which develop from auxillary buds. They protect the plants from browsing animals.
Eg : citrus, Bougainvillea etc
(iv) When the leaves of arid plants are modified into the stem becomes thick, fleshy, green & carryout photosynthesis.
Eg : Opuntia, Euphorbia
MODIFICATIONS OF STEM
(v) In grasses & strawberry, the slender sub aerial stems help in vegetative reproduction
vi) In Jasmine & mint, a slender lateral branch arises from the base of the main stem & help to produce a new plant.
(vii) In Pistia & Eichornia, it is a lateral branch with short and thick internodes & nodes with rosette of leaves and a tuft of roots
MODIFCATION OF STEM
(viii) In chrysanthemum & pineapple, it is a lateral branch of stem which originates from the basal & underground part of the main stem grows horizontally beneath the soil & comes out obliquely upward & gives rise to new leafy shoots
LEAF
🡪 Leaf is a lateral flattened structure that arises at a node from the shoot meristem.
🡪 Each leaf passes a bud in its axis known as axillary bud
🡪 A leaf has the following three parts
🡪 Leaf Base, Petiole, Lamina/Leaf Blade
1) LEAF BASE :
🡪 It attaches the leaf to the stem
🡪 In monocot plants, the leaf base expands into a sheath like structure & in dicots it may bear stipules
🡪 In members of bean family, the leaf base is swollen (Pulvinus) & helps in sleep movement.
2) PETIOLE : The stalk of the leaf
3) LAMINA / LEAF BLADE
🡪 Green expanded part of the leaf, which is main seat of Photosynthesis
🡪 It is supported by veins & vein lets, there is usually a middle prominent vein, caked the mid rib
LEAF VENATION
The arrangement of veins & vein lets in the lamina is known as venation. Veins and vein lets
(a) Provide rigidity & support to the blade.
(b) They are channels of transport of water, minerals and food materials.
TYPES OF VENATION | |
reticulate Venation | parallel venation |
Network arrangement on lamina Eg : Dicot leaf | Veins on the lamina run parallel to one another Eg : Monocot leaf |
TYPES OF LEAVES
Based on the incision of the lamina leaves are classified into
Simple & compound leaves
(a) Simple leaves – Lamina is entire or when incised, the incisors do not rundown to the midrib.
Ex : Mango, China rose
(b) Compound leaves – When its lamina is incised down to the midrib, into number of segments, called leaflets, each with a very short stalk.
Ex : Rose, Neem
A leaf has a bud in its axil, but a leaflet does not have it.
PHYLLOTAXY
The arrangement of leaves on a stem or axis.
TYPES OF PHYLLOTAXY | ||
ALTERNATE | OPPOSITE | WHORLED |
A single leaf arises at each node in an alternate manner. Examples: China rose, Sun flower | A pair of leaves arise at each node and lie opposite to each other.
Examples: Calotropis, Guava | More than two leaves arise at a node and form a whorl.
Example: Alstonia |
inflorescence
The mode of arrangement of flowers on a floral axis
(Peduncle – a stalk supporting on inflorescence)
TYPES OF INFLORESCENCE | |
Racemose Inflorescence | Cymose Inflorescence |
Ex : Caesalpinea |
Ex – Jasmine, Hibiscus |
FLOWER
🡪 Reproductive part
🡪 Modified shoot with much condensed inter node & a number of appendages(floral leaves) at a node.
🡪 Stalk of the flower – Pedicel
🡪 Calyx & corolla - Non essential whorls
🡪 Androecium & Gynoecium are reproductive whorls
SYMMETRY OF FLOWER | ||
Actinomorphic (Radial symmetry) | Zygomorphic (Bilateral symmetry) | Asymmetric (irregular) |
When a flower can be divided into 2 equal radial halves in any radial plane passing through the center Ex : Mustard, Datura, Chilly | When it can be divided into 2 similar halves only in one particular plane. Ex : Pea, Gulmohur, Bean, Cassia | It cannot be divided into 2 similar halves by any vertical planes passing through the center. Ex : Canna |
FLORAL APPENDAGES | ||
Trimerous | Tetramerous | Pentamerous |
Having flower parts, such as petals, sepals, and stamens, in sets of three. Eg : Daffodils, Orchids, Lilies | Are those flowers that exhibit sepals, stamens, petals all in sets of four. Eg : Crucifer, members of Brassicaceae | Those flowers that exhibit sepals, stamens and petals all in sets of five. Eg : petunias China rose and solanum. |
Hypogynous | Perigynous | Epigynous |
Gynoecium occupies highest position. While other parts are situated below it. The ovary in such flower is superior. Eg : Mustard, China rose, Brinjal | If Gynoecium in the center and the other part of the flower are located on the rim of the Thalamus almost at the same level. The ovary is half inferior Eg : plum, rose, peach | The margin of thalamus grows upward enclosing the ovary completely getting fused with it. Other parts of flower arise above the ovary. The ovary is inferior. Eg : Guava, cucumber, ray florets of sun flower |
POSITION OF FLORAL PARTS ON THE THALAMUS
Based on the position of calyx, corolla and androecium in respect of the ovary on thalamus, flowers are described as
parts of a flower (non essential whorls) | |
Calyx | Corolla |
Outermost whorls, sepals, protect the flower during bud condition. Gamosepalous – fused sepals Polysepalous – sepals free | Petals Brightly coloured attract insects for pollination. Gamopetalous – petals are fused Polypetalous – petals free |
parts of a flower
Based on the position of calyx, corolla and androecium in respect of the ovary on thalamus, flowers are described as
fused sepals
free sepals
fused petals
free petals
Types of aestivation | |||
Valvate | Twisted | Imbricate | Vexillary |
Margins of sepals / petals just touch one another & there is no overlapping Ex: Corolla of calotropis | Overlaps the margin of the next Ex : Corolla of Hibiscus | Posterior sepal / petal is completely internal One sepal / petal completely external Other 3 overlapped Ex : Corolla of cassia, Gulmohur | (Descendingly imbricate) Ex: Papilionaceous Corolla |
aestivation
The arrangement of sepals or petals in relation to one another in the bud conditions.
Adelphy – Union or attachment of stamens | ||
Monoadelphous | Diadelphous | Polyadelphous |
Filaments are united to form one bundle, but the anthers are free Ex : Hibiscus | Filaments are united to form two bundles & anthers remain free Ex : Pea, Bean | In few plants, filaments are united to form more than two bundles & anthers remain free Ex : Silk cotton, Lemon, Castor |
androecium
Male reproductive structure, consists of stamens or microsporophyll.
Anther contains pollen sacs or microsporangia in which numerous microspores or pollen grains are present.
types of ovary based on number of carpels | ||
Monocarpellory | Bicarpellary | Polycarpelloary |
The ovary which has only one carpel Ex – Bean | two carpels Ex – Sunflower, Tridax | more than two carpels i.e. 3. Tri carpellary 4. Tetra carpellary 5. Pentacarpellary 6. Polycarpellary Ex – Lemon |
gynoecium
Female reproductive part made up of one or more carpels
Pistil composed of one or more carpels (megasporophylls)
Syncarpous ovary | Apocarpous Ovary |
Carpels are fused Ex – Hibiscus, Mustard, Tomato, Datura, Papavar | Carpels are free Ex – Micheliachampaka, Rose, Lotus |
gynoecium
placentation
Placenta is a cushion like tissue on which the ovules are attached. The mode of attachment of ovules on the placenta is called Placentation.
Types placentation
Ex – pea, Beans
2. Axile placentation – The ovules are attached to it in a multilocular ovary.
Ex – China rose, Tomato, Lemon, ladies finger
3. Parietal placentation : Ovules develop on the inner wall the ovary or on peripheral part
Ex ; Papaya
Ovary is one chambered but it becomes two chambered due to the formation of the false septum
Ex : Mustard, Argemone
4. Free central Placentation : The ovules are borne on central axis and septa are absent
Ex – Dianthus, Primrose
5. Basal Placentation : The placenta develops at the base of the ovary & a single ovule is attached to it
Ex – Sun flower, Marigold
fruits
Botanically a fruit is a mature or ripened ovary developed after fertilization
If a fruit is formed without fertilization of the ovary, it is called a parthenocarpic fruit
The wall of the true fruit is called pericarp
PERICARP : May be dry or fleshy. When pericarp is thick and fleshy it is differentiated into outer epicarp, middle mesocarp and inner endocarp.
PARTS OF A FRUIT
MANGO COCONUT
SEED
STRUCTURE OF DICOTYEDONOUS :
A fertilized ovule develops into a seed
A seed contains two parts
A seed coat & an embryo
outer layer - Testa
Seed coat
Inner layer - tegmen
Embryo – Consists of embryonal axis with radicle & plumule at opposite ends.
🡪 A seed which contains endosperm is an endospermic seed Ex ; castor, coconut
Ex : Bean pea mustard (Dicot), Orchids – (Monocot)
🡪 A seed with two cotyledons – dicotyledonous seed Ex : Mustard, Bean, Pea
🡪 A seed with one cotyledon – Monocotyledonous seed Ex : Coconut, Orchids etc.,
SEED
STRUCTURE OF A MONOCOTYEDONOUS SEED :
SEMI TECHNICAL DESCRIPTION OF A TYPICAL FLOWERING PLANT
DESCRIPTION OF THE FAMILY FABACEAE
VEGETATIVE CHARACTERS
Trees, shrubs, herbs; root with root nodules
Stem : erect or climber
Leaves : alternate, pinnately compound or simple; leaf base, pulvinate; stipulate; venation reticulate.
Pisum sativum (Pea plant)
DESCRIPTION OF THE FAMILY FABACEAE
floral characters
Inflorescence : racemose
Flower : bisexual, zygomorphic
Calyx : sepals five, gamosepalous; valvate/imbricate aestivation
Corolla : petals five, polypetalous, papilionaceous, consisting of a posterior standard, two lateral wings, two anterior ones forming a keel (enclosing stamens and pistil), vexillary aestivation
Androecium : ten, diadelphous, anther dithecous
Gynoecium : ovary superior, mono carpellary, unilocular with many ovules, style single
Fruit : legume; seed: one to many, non-endospermic
Floral Formula :
Economic importance :
Many plants belonging to the family are sources of pulses (gram, arhar, sem, moong, soyabean; edible oil (soyabean, groundnut); dye (Indigofera); fibres (sunhemp); fodder (Sesbania, Trifolium), ornamentals (lupin, sweet pea); medicine (muliathi).
DESCRIPTION OF THE FAMILY SOLANACEAE
VEGETATIVE CHARACTERS
Plants mostly herbs, shrubs and rarely small trees
Stem : herbaceous rarely woody, aerial; erect, cylindrical, branched, solid or hollow, hairy or glabrous, underground stem in potato (Solanum tuberosum)
Leaves : alternate, simple, rarely pinnately compound, exstipulate; venation reticulate.
Solanum nigrum (makoi) plant
DESCRIPTION OF THE FAMILY SOLANACEAE
floral characters
Inflorescence : Solitary, axillary or cymose as in Solanum
Flower :bisexual, actinomorphic
Calyx : sepals five, united, persistent, valvate aestivation
Corolla : petals five, united; valvate aestivation
Androecium : stamens five, epipetalous
Gynoecium : : bicarpellary, syncarpous; ovary superior, bilocular, placenta swollen with many ovules
Fruit : berry or capsule
Seed: many, endospermous
Floral Formula :
Economic importance : Many plants belonging to this family are source of food (tomato, brinjal, potato), spice (chilli); medicine (belladonna, ashwagandha); fumigatory (tobacco); ornamentals (petunia)
DESCRIPTION OF THE FAMILY LILIACEAE
DESCRIPTION OF THE FAMILY LILIACEAE
Commonly called the ‘Lily family’ is a characteristic representative of monocotyledonous plants. It is distributed world wide.
VEGETATIVE CHARACTERS
Perennial herbs with underground bulbs/corms/ rhizomes
Leaves : mostly basal, alternate, linear, exstipulate with parallel venation
floral characters
Inflorescence : solitary / cymose; often umbellate clusters
Flower : bisexual; actinomorphic
Perianth: tepal six (3+3), often united into tube; valvate aestivation
Androecium : stamen six, 3+3, epitepalous
Gynoecium : : tricarpellary, syncarpous, ovary superior, trilocular with many ovules; axile placentation
Fruit : capsule, rarely berry
Seed: endospermous
Floral Formula :
Economic importance : Many plants belonging to this family are good ornamentals (tulip, Gloriosa), source of medicine (Aloe), vegetables (Asparagus), and colchicine (Colchicum autumnale).
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