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
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Japanese knotweed
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Bamboo
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Himalayan balsam
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Giant hogweed
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Horsetail
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Cotoneaster
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Giant rhubarb (Gunnera)
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Buddleia
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Montbretia (crocosmia)
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Rhododendron
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Three-cornered leek
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Variegated yellow archangel
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Ground elder
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.
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
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
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
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 around 1m 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
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)
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
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 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
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
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.
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.
Ground elder
Distinctive features:
Green, three-lobed leaves low to the ground (30-60cm) often forming a carpet of vegetation. White umbel-shaped flowers. Grows in shady places.
Latin name:
Aegopodium podagraria
Ability to cause damage to property:
LOW
Ability to cause damage to environment:
MEDIUM
Growth cycle:
Deciduous - with leaves emerging in late winter to early spring, and flowers forming from late spring. Dies back leaving underground rhizome system.
Flowers / Fruit / Berries:
Flowers start to bloom from late spring, white umbels that mature into oval seed capsules.
Legislation:
Non-native species but not yet covered by any legislation. More of a challenge to gardeners than in the wild at present.
Must know:
Ground elder can regenerate from small sections of rhizome, just like knotweed, and spreads quickly once introduced.
Start fixing your invasive plant problem today by requesting a survey
Request 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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Our team of experts is available between 9am and 5:30pm, Monday to Friday to answer your enquiries and advise you on the next steps
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If you already know you have an invasive plant problem, you can request a survey online in less than two minutes by providing a few brief details. A member of the team will swiftly come back to you with further information and our availability.
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Simply upload a few images of your problem plant to our identification form and one of our invasive plant experts will take a look and let you know, free of charge what you are dealing with. We’ll also be there to help with next steps where necessary.
