Characteristics of Giant Hogweed

Introduced into Britain in 1893 as an ornamental plant, Giant Hogweed escaped from domestication and proceeded to colonise areas of wasteland and riverbanks. It can grow to 5 metres tall and has a large characteristic arrangement of white flowers.

Giant Hogweed spreads very rapidly via seed dispersal and can take several years to achieve adequate control. Each plant can disperse about 50,000 seeds, so it is essential to prevent flowering.

The plant is predominantly biennial although on occasion triennial, producing a single growth of seed heads during either the second or third year. After flowering the plant dies, thus allowing the surrounding seedlings to mature.

Dangers surrounding Giant Hogweed

Giant Hogweed contains sap that on contact with human skin can cause phytophotodermititis. The effects of sap contacting the skin will become apparent 24 - 48 hours after exposure.

Post inflammatory affects include hyper-pigmentation (whitening of the skin), which once reacted with sunlight causes rapid burning, the affects can last up to 6 years.

Due to the size and nature of the flower stalks, these become attractive to children as a form of play. This can cause severe injuries to children and the results of these injuries have been well documented worldwide.

It is therefore recommended that a control regime be put in place as soon as this plant is identified.