WASTE
Defeating the
GiAnT Hogweed
Maintaining the sustainability of the uK's native plants is now seen as
paramount importance. Maxime Jay reports on a growing menace.
T
he impact of invasive alien the shape of an umbrella and produces ten of
Giant Hogweed
plants has only been identified thousand of seeds that are flattened and oval
and the government
and recognised in the last in shape. as a direct consequence of effects like these,
50 years. in 1992 at the Rio in late autumn/early winter the leaves Giant hogweed is subject to two main
Summit, all signatories of the Biodiversity turn brown, flowers die and the stems legislative acts.
convention formally recognised that the become brown and brittle. these are:
introduction of non-native species is a major it takes several years from germination n The Wildlife and Countryside Act
threat to biodiversity (second to the loss of to produce the first flowering stalk. It is 1981 (WCA)
habitat). believed to be monocarpic, i.e. dying after it is an offence to plant or otherwise cause
With the globalisation phenomenon and first flowering and then setting seed. the Giant hogweed to grow in the wild.
an increase in tourism, one could logically abundant seed production, a persistent Breaching the Wildlife and countryside act
presume that alien species have been root stalk, and vegetative reproduction from 1981 could result in criminal prosecution.
inadvertently introduced and have begun to nodule buds are cited as reasons for its n The Environmental Protection Act
settle into our native landscape although we capability to colonise rapidly and expand 1990 (EPA)
have yet to feel their impact. populations. Giant hogweed is classed as controlled
Nevertheless, let us focus on one of it thrives particularly well along water waste and any material contaminated with
the only two alien terrestrial plants in the courses, but is known to prosper in more Giant hogweed must follow the 'duty of care'
UK which are currently subject to strict inland habitats. and be disposed of adequately.
statutory requirements: the giant hogweed So what is the impact of Giant hogweed?
(Heracleum mantegazzianum). as Japanese Knotweed (Reynoutria
Giant Hogweed was first introduced japanica) its alien peer, Giant hogweed
into the UK from its original habitat in the shades out native plants creating a
caucasus region during the Victorian period monoculture consequently providing poor
as an ornamental plant. ecological conditions for wildlife and
The first record of giant hogweed in the increased risk of riverbank erosion.
UK was at the Kew Botanic Gardens in 1817 however, as opposed to Japanese
and the first naturalised population of giant Knotweed, Giant hogweed is not only a
hogweed was identified in Cambridgeshire threat to our natural environment, but is also
in 1828. regarded as a major health hazard to humans.
Giant hogweed is a perennial plant and is The stems, leaves and flowers produce a
probably one of the easiest plants to identify sap which contains furocoumarins and must
when mature. it resembles both the common be considered hazardous even when brown
hogweed (Heracleum sphondylium) and and brittle. Furthermore, unshaded habitats
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Garden angelica (Angelica archangelica) with high soil nitrate levels tend to produce
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only on a much bigger scale i.e. it can grow greater quantities of toxins in the plant.
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up to five metres tall. the sap can cause phytophotodermatitis
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it is distinguished by a dark reddish- resulting in severe and painful blisters on the
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purple to green stems that vary from 3-8 cm skin (or blindness if sap comes into contact
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in diameter. the deeply incised leaves are with eyes) when exposed to sunlight or UV-
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dark green and can grow between 1-1.5m rays. the effects may not become apparent ,

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in width. Both the stem and the leaves are for up to 48 hours after contact.

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covered with prickly hairs. these blisters can cause dark
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It flowers from late spring to autumn, pigmentation and/or scarring that can be
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with numerous white flowers bouquets in permanent or last for several years. h
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36 SuStainable SolutionS april 2009
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