Native Plant Fun Facts: The Charismatic Cow Parsnip

A cow parsnip umbel — an inverted umbrella-shaped configuration of tiny flowers. This bloom formation is common in the Apiaceae family.

This week’s featured California native plant is the cow parsnip (Heracleum maximum). It not only grows in California, but in most of the United States, and is the only plant in the genus Heracleum native to North America. While the scientific name refers to its impressive stature (How many plants are compared to the mighty mythological god who was a son of Zeus?), we were more curious about its amusing common name, which seems to arise because cows, sheep, goats and bears eat it, and the plant is related to parsnip. Does it taste like parsnip to nonhuman animals? Who knows!

A large patch of roadside cow parsnip on 7th Avenue in San Francisco, south of GFE.

Cow parsnip has broad, lobed leaves that can grow up to 16 inches wide, and the plant can get up to seven feet tall! Its small, white flowers grow in large umbels (clusters of small flowers connected to small stalks radiating from a central point like an umbrella… get it?), and attract birds, butterflies, and ladybugs. 

Hundreds of maturing cow parsnip seeds. They self-seed very easily!

Cow parsnip is a member of the Apiaceae family, which also includes edible plants such as carrots, anise, fennel, dill, celery, and parsley. Conversely, some relatives are also extremely toxic such as poison hemlock and giant hogweed (such dramatic names!). While humans can consume parts of the cow parsnip at specific growth stages, the plant’s sap can cause rashes and intense blistering for some if it gets on skin that’s then exposed to sunlight. Indigenous peoples throughout North America have many uses for it, including food, a wide variety of medicines, and for children’s toys and instruments.

A young cow parsnip plant at GFE. Take note of its grand leaves.

Cow parsnip is very hardy and versatile and commands respect in both appearance and in boundary-setting through its aforementioned sap and its prickly stems. So while you could include it in a garden and some nurseries sell it, you may want to reconsider it if you have children or it’s a highly trafficked space. Once situated, it self-seeds very easily (GFE had one plant about three years ago that self-seeded, and now we have six or seven from the parent plant), so be ready to weed it if the plant’s seeds scatter. 

The tiny, beautiful flowers of the cow parsnip. They attract birds, butterflies, and ladybugs.

Keep your eyes open for blooming cow parsnip these days! GFE’s are flowering beautifully, and you’ll likely see them on the sides of forest roads and in other wild places, too.