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 in diameter, occasionally up to 10 cm. 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 in width.
Giant hogweed is a biennial or monocarpic perennial, the plants 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 in diameter across its flat top. The plant produces 1,500 to 100,000 flattened, 1-centimetre long, oval, dry seeds that have a broadly rounded base and broad marginal ridges. Tall dead stems may mark its locations during winter.
While many plants are toxic by ingestion, Giant Hogweed causes horrendous damage to humans just by mere skin contact. Looking like an emergence from an alien planet, the Giant Hogweed can only destroy a human through cooperation with an extra-terrestrial body our Sun.
Because of its photo toxicity and invasive nature, giant hogweed is often actively removed. In the UK, the Wildlife and Countryside Act 1981 makes it an offence to plant or cause giant hogweed to grow in the wild. Hogweed is regulated as a federal noxious weed by the US government, and is illegal to import into the United States or move interstate without a permit from the Department of Agriculture. The USDA Forest Service states pigs and cattle can eat it without apparent harm. The New York State Department of Environmental Conservation has had an active program to control giant hogweed since 2008, including reporting, database maintenance, and crews for removal or herbicide control. In 2011, Maine state horticulturists, describing the plant as “Queen Anne’s lace on steroids”, reported that it has been found at 21 different locations in Maine, with the number of plants ranging from one to a hundred.
