WHAT IS GIANT HOGWEED

Despite its rather unattractive common name, the Giant Hogweed - Heracleum mantegazzianum is a large ornamental flowering plant from the Apiaceae family. This makes it a close relation to both the humble carrot and our similar, yet far smaller native cow parsley - Anthriscus sylvestris.

Native to central Asia and the Caucasus Region, the giant hogweed has become naturalised in many parts of the United kingdom, often found growing alongside footpaths and riverbanks, yet despite its unarguable beauty there is a sinister side to this plant. The sap of the the plant causes phytophotodermatitis in humans which has brought it a significant amount of bad press as well as making it an unwelcome presence in the British countryside.

Giant Hogweed was first introduced into the United Kingdom for use as an ornamental garden plant. In fact the earliest documented evidence which references this has been traced from the Royal Botanic Gardens Kew Seed List of 1817. Under its earlier scientific name of Heracleum giganteum, giant hogweed was listed among seeds supplied to the Kew by the Russian Gorecki Botanic Gardens.

From this point onwards giant hogweed became widely planted in gardens throughout Britain, however they quickly escaped from cultivation with the first naturalised population recorded in Cambridgeshire in 1828.

The problem with giant hogweed is how easily the sap is able to come in contact with the skin. Contact with the sap, particularly when exposed to to sunlight or to ultraviolet rays causes severe skin inflammations including severe blisters, chemical burns and long-lasting scars. If it comes in contact with eyes it can cause temporary or even permanent blindness. There have even been cases where excessive contact with hogweed sap has caused death.

If you suspect that you have been in contact with giant hogweed sap then cover any affect areas to prevent exposure to light and wash any skin that comes in contact with the plant immediately. Any further contact with the plant should be made wearing appropriate protective clothing.

Growing up to 5 metres in height, the giant hogweed is an impressive specimen with very large and sharply divided, dark-green leaves which have characteristic bristles underneath. The hollow green stems can be up to 10 cm in diameter and are blotched with reddish-purple spots. Each spot on the stem surrounds a hair, and there are further large, coarse white hairs which occur at the base of the leaf stalks.

The flowers are white and held in upward-facing, flat-topped clusters, These flower heads can be as large as 60 cm across and can branch branch frequently forming clusters of several flowering heads

For related articles click onto the following links:
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HOW TO RECOGNISE GIANT HOGWEED
WHAT IS GIANT HOGWEED