Identification of invasive plant species

All landowners, whether residential or commercial, have a duty to manage invasive non-native species (INNS) on their land, in accordance with the Wildlife and Countryside Act 1981 and The Invasive Alien Species (Enforcement and Permitting) Order 2019.
There are also species that are not yet legislated against that can cause real problems in gardens and on development sites

Prevent costly damage to your property

Invasive weed identification

photo of Japanese knotweed in the wild

Japanese knotweed

Distinctive features:

Asparagus-like spears or small deep red shoots in spring. Shield-shaped leaves, zig-zag stems, can reach 3m tall, bright orange rhizome

Latin name:

Reynoutria japonica

Ability to cause damage to property:

HIGH

Ability to cause damage to environment:

HIGH

Growth cycle:

Visible above ground between March and November. Dies back in winter leaving brown brittle canes

Flowers / Fruit / Berries:

Clusters of creamy white flowers in late summer. No fruit

How it spreads:

Natural rhizome spread & via contaminated soil

Legislation:

Wildlife & Countryside Act 1981

Must know:

You have a duty to declare Japanese knotweed if you sell your house, and it is your responsibility to prevent it from spreading to adjoining property. If this happens, a civil nuisance claim can be brought against you.

A forest of Bamboo

Bamboo

Distinctive features:

Green Leaves shaped like a lance or spear that taper to a point. Stem/culm rounded and thick. Tallest Bamboo will grow as high as 40 metres

Ability to cause damage to property:

HIGH depending on Bamboo type

Ability to cause damage to environment:

HIGH

Growth cycle:

Most bamboo is evergreen in the UK climate, meaning it’s visible all year round

Flowers / Fruit / Berries:

Bamboo rarely flowers (maybe once every 130 years!) and often dies afterwards.

How it spreads:

Via shallow rhizome (runners)

Legislation:

None at present, but the law might change in light of increasing awareness of bamboo's potential to spread and cause damage

Must know:

Their root balls and runners are very tough, and once established, extremely difficult to remove using everyday garden hand tools.

Himalayan balsam flowers

Himalayan balsam

Distinctive features:

Serrated spear shaped leaves grow to 25cm long in a whorl shape around green/purple stem. 2m tall. Normally found near watercourses

Latin name:

Impatiens glandulifera

Ability to cause damage to property:

LOW

Ability to cause damage to environment:

HIGH

Growth cycle:

Seedlings emerge in March and reach full size by June. Dies back in late Autumn with frosts leaving dead stalks

Flowers / Fruit / Berries:

Purple, highly scented flowers in June, turning to explosive seed pods in August/September

How it spreads:

Seed

Legislation:

Wildlife & Countryside Act 1981. The Invasive Alien Species (Enforcement and Permitting) Order 2019

Must know:

Spreads extremely quickly as each plant produces thousands of fertile seeds. You are obliged to deal with this plant if it’s on your land

Close up of Giant Hogweed white flowers and green stems

Giant hogweed

Distinctive features:

It’s huge, growing up to 5m tall

Latin name:

Heraculum mantegazzianum

Ability to cause damage to property:

LOW

Ability to cause damage to environment:

HIGH - It also has toxic sap that causes skin burns

Growth cycle:

New seedlings and established plants emerge in Spring then die back in October/November

Flowers / Fruit / Berries:

Small white flowers form in clusters on umbrella shaped flower heads that can be 50cm in diameter appear in summer

How it spreads:

Seeds - which can remain viable for up to 15 years

Legislation:

Wildlife & Countryside Act 1981. The Invasive Alien Species (Enforcement and Permitting) Order 2019

Must know:

Giant hogweed is extremely dangerous and must be professionally removed wherever it is identified

Close up on Horsetail and one of its spore carrying cones

Horsetail

Distinctive features:

Perennial plant which resembles a fern. Stripy mushroom-like cones emerge in early spring that release spores

Latin name:

Equisetum arvense

Ability to cause damage to property:

HIGH

Ability to cause damage to environment:

HIGH

Growth cycle:

Spore carrying cones emerge in March, followed by spikes of foliage that open out into 1-2m tall fern-like structures with needle shape leaves. Dies back over winter

Flowers / Fruit / Berries:

None

How it spreads:

Spore and rhizome

Legislation:

None - It’s actually a UK native

Must know:

One Horsetail fertile stalk and cone can produce thousands and thousands of spores that are suddenly released into the air and get blown on the wind for miles

close up of Cotoneaster in the wild

Cotoneaster

Distinctive features:

Woody, shrub-like stem, short, thick leaves and small berries & flowers

Latin name:

Contoneaster - horizontalis, integrifolius, simonsii, bullatus & microphyllus

Ability to cause damage to property:

MEDIUM

Ability to cause damage to environment:

HIGH

Growth cycle:

Mostly deciduous or evergreen, with new leaves emerging in late Spring

Flowers / Fruit / Berries:

Produces flowers called panicles. Red berries appear in Autumn

How it spreads:

Seed dispersal

Legislation:

Schedule 9 of the Wildlife and Countryside Act 1981

Must know:

It comes in hundreds of different varieties but only 5 are considered invasive here in the UK

Giant Rhubarb (Gunnera) growing in the wild

Giant rhubarb (Gunnera)

Distinctive features:

Large jagged edged leaves, spiky stems, looks like dinosaur food! Around 2m tall when fully grown

Latin name:

Gunnera tinctoria

Ability to cause damage to property:

LOW

Ability to cause damage to environment:

HIGH

Growth cycle:

March to November, although crowns and dried flower cones are likely to remain visible in winter

Flowers / Fruit / Berries:

1m long red cones of small flowers turn to small reddish berries, then black seeds

How it spreads:

Seed and rhizome

Legislation:

Wildlife and Countryside Act 1981. The Invasive Alien Species (Enforcement and Permitting) Order 2019

Must know:

The species is particularly frequent along the banks of watercourses and is becoming a real nuisance in the UK and Ireland

Close on on a buddleia plant with purple flowers

Buddleia

Distinctive features:

Small, brightly-coloured flowers grouped in conical shape. Stems look woody with thick hairs running up and down them

Latin name:

Buddleia davidii

Ability to cause damage to property:

HIGH

Ability to cause damage to environment:

MEDIUM

Growth cycle:

Deciduous - with leaves emerging in Spring, and flowers forming from June - September

Flowers / Fruit / Berries:

Flowers start to bloom from early to late Summer, concentrating in the shape of a cone growing up to 10 inches in length at the end of each branch

How it spreads:

Seed

Legislation:

Not illegal, but the law could change as Buddleia causes nearly £1 million worth of damage to UK buildings every year and is a huge problem for the country’s railway network

Must know:

A single buddleia plant can produce over 1 million seeds per year

Montbretia 6

Montbretia Crocosmia x Crocosmiiflora

Distinctive features:

Grass like leaves, bright orange flowers

Latin name:

Crocosmia x crocosmiiflora

Ability to cause damage to property:

LOW

Ability to cause damage to environment:

HIGH

Growth cycle:

Grass-like shoots appear in early spring, with flower spikes emerging in high summer. Dies back in winter

Flowers / Fruit / Berries:

Colourful, red-orange flowers shaped like a funnel which remain for most of the summer and into early autumn

How it spreads:

Although it does produce seeds, most of its reproduction takes place vegetatively

Legislation:

Wildlife and Countryside Act 1981

Must know:

Particularly common on roadsides and coastal areas. Underground, it grows from corms that look a bit like bulbs

A close up of Rhododendron Ponticum growing in the wild

Rhododendron Ponticum

Distinctive features:

Dark green, thick, glossy leaves that are evergreen. Woody stems become more like the trunk of a tree as it ages

Latin name:

Rhododendron ponticum

Ability to cause damage to property:

LOW

Ability to cause damage to environment:

HIGH

Growth cycle:

Evergreen and therefore visible all year round

Flowers / Fruit / Berries:

Colourful, light purple flowers form in funnel-shaped blooms during early summer

How it spreads:

Seed spread occurs following flowering of mature plants. It can also form new roots from collapsed branches that touch the ground (stem layering)

Legislation:

Wildlife and Countryside Act 1981

Must know:

Rhododendron acidifies the soil in which it grows, making it extremely difficult for other plants to survive, even after it has been removed

Three-cornered leek 2

Three-cornered leek

Distinctive features:

Unique triangular stem. Slender, strap-like leaves that are three-angled

Latin name:

Allium triquetrum

Ability to cause damage to property:

LOW

Ability to cause damage to environment:

HIGH

Growth cycle:

Starts its lifecycle as a seed or bulb, flowers typically in spring and early summer. Plant dies back in winter but the bulbs beneath the soil store energy for the next year.

Flowers / Fruit / Berries:

Produces white, star-shaped flowers arranged in clusters resembling an umbrella at the apex of its stem.

How it spreads:

Reproduces both by seed and bulb.

Legislation:

Wildlife & Countryside Act 1981.

Must know:

Grows in woodlands, meadows, gardens, and long verges.

VYA 2

Variegated yellow archangel

Distinctive features:

Leaves grow in pairs along the stems and have a serrated or toothed edge. Leaves arranged like wings.

Latin name:

Lamiastrum galeobdolon argentatum

Ability to cause damage to property:

LOW

Ability to cause damage to environment:

HIGH

Growth cycle:

Starts its growth cycle in Spring, to then begin its vegetative growth in late spring and summer. After flowering, the plant will form seeds and spread. In winter, the plant may enter a period of stagnation, while its leaves will remain visible as they’re evergreen.

Flowers / Fruit / Berries:

Produces small, yellow flowers.

How it spreads:

After flowering, the plant will form seeds, developing into small capsules to colonise new areas.

Legislation:

Wildlife & Countryside Act 1981.

Must know:

If undisturbed, it may spread 1-2 lateral metres by natural runners in one growing season.

Start fixing your invasive plant problem today by requesting a survey

Rest assured, where invasive species are identified at an early stage and tackled correctly, problems can usually be avoided. Our specialist consultants complete thorough surveys to identify the extent of the problem. Our plans aren’t one-size-fits-all; they’re customised to tackle the invasive species at your property effectively, taking account of all of your requirements. 

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