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Giant hogweed

Heracleum mantegazzianum
Herkulesstaude fg01.jpg
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Apiales
Family: Apiaceae
Genus: Heracleum
Species: H. mantegazzianum
Binomial name
Heracleum mantegazzianum
Sommier & Levier

Heracleum mantegazzianum, commonly known as giant hogweed,cartwheel-flower,giant cow parsnip,hogsbane or giant cow parsley, is a plant in the family Apiaceae. In New Zealand, it is also sometimes called wild parsnip, or wild rhubarb. It typically grows to heights of 2–5.5 m (6 ft 7 in–18 ft 1 in). Superficially, it resembles common hogweed (Heracleum sphondylium), Heracleum sosnowskyi, or garden angelica (Angelica archangelica). It is phototoxic and considered to be a noxious weed in many jurisdictions. Giant hogweed is native to the Caucasus region and Central Asia. It was introduced to Britain as an ornamental plant in the 19th century, and it has also spread to many other parts of Europe, the United States, and Canada.

The sap of giant hogweed causes phytophotodermatitis in humans, resulting in blisters and long-lasting scars. These serious reactions are due to the furocoumarin derivatives in the leaves, roots, stems, flowers, and seeds of the plant.

Giant hogweed has a stout, bright green stem that is frequently spotted with dark red and hollow red-spotted leaf stalks that produce sturdy bristles. The stems grow to more than 2 m high. The hollow stems vary from 3–8 cm (1.2–3.1 in) in diameter, occasionally up to 10 cm (3.9 in). Each dark red spot on the stem surrounds a hair, and large, coarse white hairs occur at the base of the leaf stalk. The plant has deeply incised compound leaves which grow up to 1–1.7 m (3 ft 3 in–5 ft 7 in) in width.

Giant hogweed is a biennial or monocarpic perennial, the plants usually begin dying after they have set seed. It usually flowers in its second year from late spring to midsummer, with numerous white flowers clustered in an umbrella-shaped head that is up to 80 cm (31 in) in diameter across its flat top. The plant produces 1,500 to 100,000 flattened, 1-centimetre (0.39 in)-long, oval, dry seeds that have a broadly rounded base and broad marginal ridges. Tall dead stems may mark its locations during winter.


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Wikipedia

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