Invasive Plant Species

Identification Workshop: reducing risk and protecting biodiversity

Agenda

Understanding Invasive Species

Invasive Plant Species: Their Impact and the Importance of Early Detection

Recognizing invasive species is crucial for protecting our ecosystems and biodiversity from harm

Invasive species can cause significant damage to native ecosystems, making early identification essential for effective management. Some species have potentially costly legal implications.

Identifying and managing this invasive plant species is crucial for our environment

Japanese Knotweed threatens ecosystems by outcompeting native plants. The presence of Japanese Knotweed on a property can have serious legal and cost implications. Early identification is essential for effective management and prevention of further spread.

Leaves

Young leaves are dark red/purple and start furled before spreading out and becoming green.

Stems

By late Spring, the stems can grow to chest height, becoming hollow and speckled with red/purple.

Shoots

In spring, Japanese Knotweed shoots emerge, growing rapidly and creating visible clusters. They resemble asparagus spears and are often red/green in hue.

Flowers

In late Summer, plumes of small, densely clusters off-white flowers appear.

Leaves

During summer, the plant reaches its full height, overshadowing surrounding vegetation. Large heart-shaped leaves, 10-15cm in length that alternate along the stem.

Canes

Canes grow to 2-3 metres, forming dense thickets. The bamboo-like canes are predominately green but can also present in red hues.

Rhizome

Above-ground vegetation can almost completely disappear as the plant senesces over winter. The plant is dormant, not dead!

Canes

Stems brown before desiccating and becoming brittle, looking much like dead bamboo.

Leaves

Leaves begin to yellow before dropping off entirely.

Peony Shoots

Commonly mistaken for JKW in early Spring, with both producing reddish, asparagus-like spears. Aside from tone variations, JKW stems feature an ochrea (a papery sheath wrapping around the stem at the nodes), whereas Peony does not.

Dogwood

Similarly shaped leaves, reddish stems and cream-white flowers, but the foliar growth pattern is different (paired vs alternating/’zig-zag’).

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Russian Vine

Has similarly coloured flowers and an aggressive growth rate to match JKW, but grows on a vine rather than a cane.

Peony Shoots

Commonly mistaken for JKW in early Spring, with both producing reddish, asparagus-like spears. Aside from tone variations, JKW stems feature an ochrea (a papery sheath wrapping around the stem at the nodes), whereas Peony does not.

Dogwood

Similarly shaped leaves, reddish stems and cream-white flowers, but the foliar growth pattern is different (paired vs alternating/’zig-zag’).

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Russian Vine

Has similarly coloured flowers and an aggressive growth rate to match JKW, but grows on a vine rather than a cane.

Creating invasive monocultures throughout UK riverbanks

Himalayan Balsam spreads rapidly, outcompeting native plants, leading to loss of biodiversity and increased erosion in affected areas. It is often found dominating riverbanks and streams throughout the UK.

Autumn/Winter

In autumn, the plant dies back and dry, hollow stems remain.

Summer

In summer, the plant blooms with bright pink flowers attracting pollinators.

Spring

In spring, Himalayan Balsam emerges with distinctive green shoots.

Many seeds often end up in rivers, carried away downstream to colonise new areas.

Explosive Dispersal

As the pods ripen, they come under tension (like a coiled spring). Even a small disturbance or touch will cause them to explode, sending seeds up to 7 metres away!

Seed Pods

2-3cm in length, each pod contains up to a dozen seeds.

Rosebay Willowherb

Can be confused with HB at a distance due to their similarly-coloured flowers, but the arrangement differs greatly; Rosebay flowers appear on a “spear”, whereas HB features drooping clusters

A dangerous invasive plant posing threats to ecosystems and health

Contact with Giant Hogweed’s phototoxic sap can cause severe skin burns and life-long UV sensitivity to the affected area. Do Not Touch!

Stems

Ridged and hollow, stems thicken rapidly and have distinctive purple blotches and white hairs.

Leaves

Jagged leaves that resemble a giant parsley or celery leaf.

Rosettes

Emerges as a basal rosette. Early growth can be mistaken for cow parsley, but it is much larger.

Stems

Ridged and hollow, covered in purple blotches and up to 10cm wide. Where most of the toxic sap is stored!

Leaves

Giant, serrated leaves up to 1.5 metres wide. Dark green, deeply defined lobes with hairy undersides

Flowers

Massive flower heads up to 60cm wide containing hundreds of small white flowers in umbrella-like clusters

Stems

Stems turn brown and brittle, but often remain standing throughout winter.

Leaves

Leaves yellow, die back and drop off.

Flowers

Flowers die back but dry, brown seedheads remain.

Cow Parsnip

The leaves present with 3 main lobes and are significantly less jagged than those of Giant Hogweed.

Common Hogweed

The leaves of the common variety are less jagged and more rounded than those of Giant Hogweed, nor do the stems feature blotchy purple spots.

Woodland Angelica

Often mistaken for Giant Hogweed, Angelica leaves are divided into leaflets, which are themselves divided again, whereas Giant Hogweed leaves are only divided once.

What Can You Do?

Report sightings to your Local Authority