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Giant Hogweed

Scientific name: Heracleum mantegazzianum
AKA: Efwr enfawr (Welsh)
Native to: Caucasus mountains in south west Russia and Georgia
Habitat: Widespread, most common on river banks
Easy to identify when fully grown by height, size of leaves and size of flowers. Can be confused with native hogweed (cow parsley) when not fully grown or when growth is stunted (e.g. regrowth after cutting). Introduced as an ornamental. First recorded wild in the UK in the late 19th century. Spreads solely by seeds, mainly through deliberate planting, wind dispersal and in water courses. Now common across much of the UK. Contact with any part of this plant must be avoided as even minute amounts of sap can cause blistering of the skin following exposure to sunlight. Other negative impacts include out-competing native flora, river bank erosion and increase in flood risk. Can cause delays/ additional costs on development sites where the plant must be removed as controlled waste in order to comply with legislation under the Environmental Protection Act, 1990. Giant hogweed is listed under Schedule 9 to the Wildlife and Countryside Act 1981 with respect to England, Wales and Scotland. As such it is an offence to plant or otherwise cause this species to grow in the wild.

To see how the River Severn Custodians tackles this invasive in our area, click on How to tackle Giant Hogweed.



Sampling on our stretch of the river Severn in 2012 identified Giant Hogweed balsam in the locations marked by red dots, below.