Cow parsnip

Cow parsnip is a large herbaceous plant in the carrot family, usually treated as *Heracleum maximum*, a native North American species.

Cow parsnip is a tall herbaceous plant in the carrot family, native to North America. It is known for its large white flower clusters and sap that can cause skin irritation upon sunlight exposure. The species, usually treated as *Heracleum maximum*, is found across Canada in moist, open habitats.

Description

Cow parsnip is a large herbaceous biennial or short-lived perennial, typically reaching 1–3 m in height. It has broad, compound leaves, thick hollow stems, and flat-topped white flower umbels up to 30 cm across. It is one of the largest native members of the carrot family (Apiaceae) in North America.

Distribution and habitat

The species occurs across much of North America, including many parts of Canada, especially in cooler regions. It is most common in moist, partially shaded or open habitats such as streambanks, floodplains, meadows, woodland edges, and damp roadsides. It thrives in areas with ample moisture.

Uses and cultural significance

Cow parsnip has a history of use as a food and medicinal plant, particularly in Indigenous North American traditions. Edible parts have included young shoots, stems, roots, flowers, and seeds. However, harvesting requires caution because the sap can cause skin irritation.

Safety

The plant’s sap contains phototoxic chemicals called furanocoumarins. Skin contact followed by sunlight exposure can cause phytophotodermatitis, ranging from mild irritation to blistering. This reaction is similar to that caused by the invasive Giant Hogweed, though cow parsnip is generally less dangerous.