giant hogweed
(Heracleum mantegazzianum)
An alien invasive species and noxious weed, introduced in the 19thC as an ornamental and now widespread throughout Britain, especially on river banks and in other damp areas. The sap and hairs on the leaf and stem are toxic, causing severe skin irritation and blistering following exposure to sunlight. Symptoms take a day or two to develop but can last for several months or even years. Giant hogweed is native to the Caucasus and central Asia.
This definition is abridged from A – Z of tree terms: A companion to British arboriculture.
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