Cow Parsnip

Cow parsnip (Heracleum maximum) is native to North America and grows in a variety of habitats including woodlands, forest openings, grasslands, stream and river edges and along roadsides. Its sap contains a phototoxin that reacts with ultraviolet light to cause skin irritation ranging from a mild rash to severe blistering.

Identification

This biennial plant flowers in its second year and has a flower stem that may grow more than 6 feet tall. The flower head, made up of numerous small white flowers, is close to a foot across. The plant's leaves can be almost 2 feet wide.

First year plants grow basal rosettes (low clusters of leaves growing directly from the roots) of big coarse hairy leaves divided into 3 deeply lobed leaflets. The leaves have more rounded lobes than the more deeply cut leaves of giant hogweed which usually have more pointed lobes.

Due to its size and similar appearance, cow parsnip is often misidentified as giant hogweed. However, the stem of cow parsnip does not contain the purple blotches that are found on giant hogweed stems. For a full comparison of giant hogweed and cow parsnip, see the DEC webpage on giant hogweed.

Preferred Habitats

Cow parsnip is relatively uncommon in New York, and is most often found in the cooler parts of the state. Typical habitats are usually near water and in rich, moist soil, often along stream banks, in meadows, and in wet ditches. It also grows well in partial shade along roads and in floodplain forests. Cow parsnip blooms in late May to late June, which is typically earlier than giant hogweed.

Unlike the invasive introduced species giant hogweed and wild parsnip, cow parsnip is native to North America and is found almost everywhere in the U.S. except the south. It is very cold-hardy, and is most abundant in the Pacific Northwest and Alaska, where it has a long history of use as a food and medicinal plant.

Protect Yourself

Like giant hogweed sap, cow parsnip sap contains furanocoumarins (fyur-a-no-coo-MAR-inz), phototoxic chemicals that are activated by ultraviolet rays in sunlight. If the sap gets on skin and is then exposed to sunlight, it can cause a blistering itchy rash. Cow parsnip is not considered to be as toxic as giant hogweed, but like its smaller relative, wild parsnip, it can still cause nasty burns that take weeks or months to heal and can leave scars. If the plant touches your skin, immediately wash the area with soap and water and protect from sunlight for 48 hours.