Giant Hogweed - Heracleum mantegazzianum

This is a very robust plant that can reach 5 metres in height. Stems are ridged, red spotted and up to 10 cm diameter. Leaves are often very large and are pinnately divided with broad toothed and lobed divisions. The inflorescence is a compound umbel up to 50 cm across and with 50 to 150 rays. It has no bract and several bracteoles. The flower colour is white. Beware as any contact with this plant can cause a rash or serious burning of the skin.

A very robust plant - several metres tall.  Flattened seeds, with persistent sepals and large conspicuous oil-bodies

Various habitats including damper areas and water margins as well as roadsides and wasteland.

Flowers June to August.

Biennial. Each giant hogweed plant is capable of producing about 50,000 seeds and, though they only drop close to the plant, they can be transported on shoe soles to other areas. The seeds remain viable for seven years meaning that eradication is a long and expensive process.

Widespread and although still occasional it is increasing.

In Stace (4th edition) it is noted that there may be several similar species 

Infrequent in Leicestershire and Rutland.  In the 1979 Flora survey of Leicestershire it was found in 16 of the 617 tetrads.

In the current Checklist (Jeeves, 2011) it is listed as Alien; neophyte; locally frequent in the Market Bosworth area; occasional elsewhere