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Giant Hogweed

2007 Schools Wikipedia Selection. Related subjects: Plants

                iGiant Hogweed
           Scientific classification

   Kingdom:  Plantae
   Division: Magnoliophyta
   Class:    Magnoliopsida
   Order:    Apiales
   Family:   Apiaceae
   Genus:    Heracleum
   Species:  H. mantegazzianum

                                Binomial name

   Heracleum mantegazzianum
   Sommier & Levier

   Giant Hogweed (Heracleum mantegazzianum), or Giant Cow-parsley, is a
   member of the family Apiaceae, native to the Caucasus Region and
   Central Asia.

   As its name indicates, it is characterized by its size and may grow
   2-5m (rarely to 7 m) tall. Except for size, it closely resembles Common
   Hogweed (Heracleum sphondylium), Heracleum sosnowskyi or Garden
   Angelica (Angelica archangelica).

   It is further distinguished by a stout, dark reddish-purple stem and
   spotted leaf stalks that are hollow and produce sturdy bristles. Stems
   vary from 3-8 cm in diameter, occasionally up to 10 cm. The stem shows
   a purplish-red pigmentation with raised nodules. Each purple spot on
   the stem surrounds a hair, and there are large, coarse white hairs at
   the base of the leaf stalk. The plant has deeply incised compound
   leaves which grow up to 1-1.7 m in width.

   Giant Hogweed is a perennial with tuberous rootstalks which form
   perennating buds each year. It flowers from late spring to mid summer,
   with numerous white flowers clustered in an umbrella-shaped head that
   is up to 80 cm (2.5 ft) in diameter across its flat top.

   The plant produces flattened, 1cm long, oval dry seeds that have a
   broadly rounded base, and broad marginal ridges.

   The Giant Hogweed flowers from late spring to mid summer, and then
   produces numerous, large flattened elliptic dry seeds (between
   1,500-100,000). Shoots die down in the fall. Tall stems mark its
   locations during winter.

   Many foreign plants were introduced to Britain in the 19th century,
   mainly for ornamental reasons. A few have become aggressively dominant,
   creating serious problems in some areas. It is now widespread
   throughout the British Isles especially along riverbanks. By forming
   dense stands they can displace native plants and reduce wildlife
   interests. It has also spread in the northeastern and northwestern
   United States. It is equally a pernicious invasive species in Germany,
   France and Belgium, overtaking the local species. It was introduced in
   France in the 19th century by botanists, much appreciated by
   beekeepers.

   In the UK the Wildlife and Countryside Act 1982 makes it an offence to
   plant or cause Giant Hogweed to grow in the wild.

Toxic

   Giant Hogweed is a phototoxic plant. Its sap can cause photodermatitis,
   skin inflammations when the skin is exposed to sunlight or to UV-rays.
   Initially the skin colours red and starts itching. Then blisters form
   as in burns within 48 hours. They form black or purplish scars, which
   can last several years. Hospitalisation may become necessary. Presence
   of minute amounts of sap in the eyes, can lead to temporary or even
   permanent blindness. These reactions are caused by the presence of
   linear derivatives of furocoumarin in its leaves, roots, stems,
   flowers, and seeds. These chemicals can get into the nucleus of the
   epithelial cells, forming a bond with the DNA, causing the cells to
   die. The brown colour is caused by the production of melanin by
   furocoumarins. In Germany, where this plant has become a real nuisance,
   there were about 16,000 victims in 2003.
   Giant Hogweed (close-up)
   Enlarge
   Giant Hogweed (close-up)

   Keep children away from this plant. Wear protective clothing when
   handling it if you dig plants; consider wearing eye protection.
   Chopping out the root is feasible, but may have to be done several
   times as the plant re-grows. Wash off exposed skin thoroughly with soap
   and water and protect the exposed skin from the sun for several days.

   Keep the plant mowed down during the summer to prevent seeds from
   maturing. Don't allow pieces of it to land on bare skin. Even after the
   parent plant is completely removed, the numerous seeds left behind can
   come up, 7 to 15 years later. Ongoing monitoring is required. Removing
   the green growth will help to exhaust the root and will weaken the
   plant, so digging it out (as far as 60 cm deep) and chopping it is
   feasible.

   2,4-D, TBA, MCPA and dicamba will kill above ground parts but are
   reportedly not particularly effective on persistent rootstalks.
   Glyphosate ( Roundup) is considered the most effective herbicide and
   should be used cautiously around desirable species since it is
   nonselective. Application during bud stage and while the plant is
   actively growing is recommended by New York Cooperative Extension.
   A warning in Peterborough, England
   A warning in Peterborough, England
   Retrieved from " http://en.wikipedia.org/wiki/Giant_Hogweed"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
