Non-native plant species are frequently found along river corridors in urban areas. This reflects the numerous potential sources of these species in urban areas, including domestic gardens, public parks, road and rail verges, abandoned land, and golf courses, and also the ability of rivers to collect, disperse and deposit seeds during spates.
Numerous non-native plant species may be present in the vegetation and soil seed bank, and a few of these can become invasive to the extent that they cause significant problems for native vegetation. The Environment Agency recently identified seven non-native plant species that have caused serious problems within rivers and along river banks across Britain: Himalayan balsam (Impatiens glandulifera), Japanese knotweed (Fallopia japonica), Giant Hogweed (Heracleum mantegazzianum), Floating pennywort (Hydrocotyle ranunculoides), Australian swamp stonecrop (Crassula helmsii), Parrot’s feather ((Myriophyllum aquaticum), Creeping water primrose (Ludwigia grandiflora).
American Skunk Cabbage (Lysichiton Americanus)
More info: DEFRA, Nature Locator
Buddleia (Buddleja Davidii)
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Cabbage-palm (Cordyline Australis)
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Canadian Fleabane (Conyza Canadensis)
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Cape Goosberry (Physalis Peruviana)
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Confused Michaelmas-Daisy (Aster Novi-Belgii)
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Fig (Ficus Carica)
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Floating Pennywort (Hydrocotyle Ranunculoides)
More info: DEFRA, Nature Locator
Foxglove Tree (Paulownia Tomentosa)
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Giant Hogweed (Heracleum Mantegazzianum)
More info: DEFRA, Nature Locator
Giant Rhubarb (Gunnera Tinctoria)
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Himalayan Balsam (Impatiens Glandulifera)
More info: DEFRA, Nature Locator
Hoary Cabbage (Hirschfeldia Incana)
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Italian Alder (Alnus Cordata)
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Ivy-leaved Toadflax (Cymbalaria Muralis)
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Japanese Knotweed (Fallopia Japonica)
More info: DEFRA, Nature Locator
Large Evening Primrose (Oenothera Glazioviana)
More info: DEFRA
Mexican Fleabane (Erigeron Karvinskianus)
More info: DEFRA
Monkeyflower (Mimulus Guttatus)
More info: DEFRA, Nature Locator
New Zealand Pigmyweed (Crassula Helmsii)
More info: DEFRA, Nature Locator
Parrot’s Feather (Myriophyllum Aquaticum)
More info: DEFRA, Nature Locator
Rape (Brassica Napus)
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Shaggy Soldier (Galinsoga Quadriradiata)
More info: DEFRA
Small Balsam (Impatiens Parviflora)
More info: DEFRA
Snowberry (Symphoricarpos Albus)
More info: DEFRA
Sweet Pepper (Capsicum Annuum)
More info: DEFRA
Tomato (lycopersicon Esculentum)
More info: DEFRA
White Melilot (Melilotus Albus)
More info: DEFRA
Yellow-flowered Strawberry (Potentilla Indica)
More info: DEFRA