Angiosperms (Flowering Plants) • Earth.com

Giant hogweed

(Heracleum mantegazzianum)

galery
en

Description

Heracleum mantegazzianum, commonly known as giant hogweed, is a monocarpic perennial herbaceous flowering plant in the carrot family Apiaceae. H. mantegazzianum is also known as cartwheel-flower, giant cow parsley, giant cow parsnip, or hogsbane. In New Zealand, it is also sometimes called wild parsnip (not to be confused with Pastinaca sativa) or wild rhubarb. Giant hogweed is native to the western Caucasus region of Eurasia. It was introduced to Britain as an ornamental plant in the 19th century, and has also spread to other areas in Western Europe, the United States, and Canada. Its close relatives, Sosnowsky's hogweed and Persian hogweed, have similarly spread to other parts of Europe. The sap of giant hogweed is phototoxic and causes phytophotodermatitis in humans, resulting in blisters and scars. These serious reactions are due to the furanocoumarin derivatives in the leaves, roots, stems, flowers, and seeds of the plant. Consequently, it is considered to be a noxious weed in many jurisdictions. Giant hogweed typically grows to heights of 2 to 5 m (6 ft 7 in to 16 ft 5 in). Under ideal conditions, a plant can reach a height of 5.5 m (18 ft 1 in). The leaves are incised and deeply lobed. A mature plant has huge leaves, between 1–1.5 m (3 ft 3 in – 4 ft 11 in) wide, and a stout, bright green stem with extensive dark reddish-purple splotches and prominent coarse white hairs, especially at the base of the leaf stalk. Hollow, ridged stems vary from 3–8 cm (1–3 in) in diameter, occasionally up to 10 cm (4 in) in diameter and can grow to more than 4 m (13 ft) high. Dark red spots on the stem each surround a single hair. The umbrella-shaped inflorescence, called a compound umbel, may be up to 100 cm (3 ft 3 in) in diameter across its flat top. The flowers are white or greenish white and may be radially symmetrical or strongly bilaterally symmetrical (zygomorphic). The fruits are schizocarps, producing seeds in dry, flattened, oval pairs.  Each seed is approximately 1 cm (1⁄2 in) in length, with a broadly rounded base and broad marginal ridges, tan in color with brown lines (so-called oil tubes) extending ¾ of the length of the seed. During the first few years of growth, the leaves and stem of a pre-flowering plant die over the winter. In the spring, the plant grows back from its root. In other words, the giant hogweed is a herbaceous perennial.

Taxonomic tree:

Domain:
Kingdom: Plantae
Phylum: Magnoliophyta
Class: Magnoliopsida
Order:Apiales
Family:Apiaceae
Genus:Heracleum
News coming your way
The biggest news about our planet delivered to you each day