What is Giant Hogweed?

Giant hogweed is a large plant native to Asia that has made its way around the world. It can grow 15 to 20 feet (4.5 to 6 m) tall with a stem that has a diameter of 2 to 4 inches (5 to 10 cm). The leaves of this plant grow to about 5 feet (1.5m) in width. It has lacy, white umbel flowers that can reach a diameter of 2.5 feet (0.7 m).

This plant was introduced into the United States around 1917 as an ornamental garden plant. It has escaped cultivation and become well established in many parts of the country. It is found abundantly in the western part of New York State, Connecticut and Massachusetts. It also flourishes on the west coast of the United States in Oregon and Washington, as well as in Canada and throughout Europe.

Hogweeds are very adaptive and can thrive in a wide range of habitats. It lives on river banks, near streams, on roadsides, in vacant lots, in yards and gardens or in any other cool, wet areas. It spreads fairly slowly, but persistently.

Humans should steer clear of giant hogweed. It secretes a clear toxic sap which makes the skin very sensitive to ultraviolet (UV) rays. Contact with the sap quickly results in painful blisters, third degree burns and permanent scarring. If any comes in contact with the eyes, it can cause temporary or sometimes even permanent blindness. Giant hogweed is especially dangerous to children, who are attracted to areas where this plant likes to grow. Its large hollow stalk is appealing to some for makeshift weapons and pea shooters.

Giant hogweed is hazardous not only to humans, but also to the environment. As an invasive species, it destroys native plants and disrupts ecosystems by competing with other plants for sunlight, space and nutrients. This in turn affects animal life by reducing the food supply derived from native species of plants.

When this plant dies in the fall, it contributes to soil erosion along river and stream banks where it grows. Since it replaces native species whose roots normally remain and hold the soil in place, giant hogweed causes the soil it grows in to easily wash away. It also contributes to wind erosion in some of its habitats for the same reason.

In the United States, giant hogweed is on the federal government’s noxious weed list and further imports of this plant are illegal. It is also illegal to transport the plant from state to state or even within a state. Besides trying to prevent further introduction of the plant, attempts to control giant hogweed include the use of herbicides and mechanical removal, which are only minimally effective due to the plant's hardiness and adaptive capabilities.