Giant Hogweed (Heracleum mantegazzianum) is closely related to Cow-Parsley. Its flower-covered stems are tall, generally 2-3m in height, and the flowering heads can reach a width of up to 80cm. The lower leaves are smaller, with a height of around 1m, and are spiky.
This plant is seen throughout the UK, and grows alongside rivers and in rough pastures such as damp crofts.
Giant Hogweed was introduced to gardens in the 1820s, and was planted deliberately alongside rivers and ponds.
Hogweed is a self-fertilizing plant and produces seeds in vast numbers (20-50,000), which can survive in the soil for over 3 years before sprouting.
The sap of Giant Hogweed is toxic, and can cause serious burns; it is extremely important that you do not touch it if you come across it. Dogs have also been known to get burnt, so it is important that they stay away from the plant too!