Heracleum lanatum Michx.
Heracleum maximum (synonym: Heracleum lanatum), commonly known as cow parsnip, is the only member of the genus Heracleum native to North America. H. maximum is also known as Indian celery, Indian rhubarb or pushki.
The classification of this species has caused some difficulty. Recent authoritative sources have referred to it variously as Heracleum maximum, Heracleum lanatum, or as a subspecies or variety of Heracleum sphondylium, either Heracleum sphondylium subsp. montanum or Heracleum sphondylium var. lanatum. The classification given here follows ITIS.
Cow parsnip is distributed throughout most of the continental United States except the Gulf Coast and a few neighboring states. It occurs from sea level to elevations of about 2,700 metres (9,000 ft). It is especially prevalent in Alaska, where it is often found growing amongst plants like devil's club, which is nearly identical in size and very similar in appearance, and monkshood, a very toxic flower. In Canada, it is found in each province and territory, except Nunavut. It is listed as "Endangered" in Kentucky and "Special Concern" in Tennessee.
Cow parsnip is a tall herb, reaching to heights of over 2 metres (7 ft). The genus name Heracleum (from "Hercules") refers to the very large size of all parts of these plants. Cow Parsnip has the characteristic flower umbels of the carrot family (Apiaceae), about 20 centimetres (8 in) across; these may be flat-topped or rounded, and are always white. Sometimes the outer flowers of the umbel are much larger than the inner ones. The leaves are very large, up to 40 cm (16 in) across, and divided into lobes. The stems are stout and succulent. The seeds are 8–12 mm (0.3–0.5 in) long and 5–8 mm (0.2–0.3 in) wide.
The stems and leaves contain furocoumarins, chemicals responsible for the characteristic rash of erythematous vesicles (burn-like blisters) and subsequent hyperpigmentation that occurs after getting the clear sap onto one's skin. The chemical is photosensitive, with the rash occurring only after exposure to ultraviolet light. Because of this, phytophotodermatitis may occur after cutting or mowing the plants on a sunny day.
Indigenous North Americans have had a variety of uses for cow parsnip. It could be an ingredient in poultices applied to bruises or sores. The young stalks and leaf stems were used for food once the outer skin was peeled off. The dried stems were used as drinking straws for the old or infirm, or made into flutes for children.
- Norman F. Weeden (1996), A Sierra Nevada Flora, Wilderness Press, ISBN 0-89997-204-7
- "Heracleum maximum". Natural Resources Conservation Service PLANTS Database. USDA. Retrieved 2008-03-30.
- Elizabeth L. Horn (1998), Sierra Nevada Wildflowers, Mountain Press, ISBN 0-87842-388-5
- "Heracleum maximum: Similar Species". iNaturalist.org. iNaturalist. Retrieved 2018-08-26.
- "Giant Hogweed, Heracleum mantegazzianum". maine.gov. State of Maine: Department of Agriculture, Conservation, and Forestry. Retrieved 2018-08-26.
- "BRIT - Native American Ethnobotany Database". herb.umd.umich.edu.
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