Plant Profile: Cow Parsnip (Heracleum maximum)

During recent walks atop Mt. Sutro, I found a fair amount of native Cow Parsnip (Heracleum maximum, syn. H. lanatum). With its large green leaves and huge stems, this local resident is an impressive sight.

What’s in a Name?

Heracleum maximum is a member of the Apiaceae (Carrot or Parsley) family. The Heracleum genus is thought to be named for Hercules due to his great strength and size, and for also being the first to use the plant for medicine. Other common names for this species are Indian celery, Indian rhubarb, and Pushki. Note that Heracleum maximum is the only member of this genus that is native to North America. In California it can be found primarily in the northern half of the state.

Characteristics

Cow Parsnip is a perennial herb. It is tall and can grow up to 7 feet. The stem is erect, hairy and hollow and each leaf is ternate (having 3 leaflets). The flowers are large white umbels (stalks spread from a common point like umbrella ribs) and its fruit is oblong (.3-.4 inches) with very fine hair. Some think the fruit has a disagreeable smell.

You’ll notice this plant for its huge leaves and large white umbel flowers – though don’t mistake it for other similar plants in the Apiaceae family, such as the highly toxic and invasive Poison Hemlock (Conium maculatum), or the Giant Hogweed (Heracleum mantegazzianum). Poison Hemlock, which is prevalent throughout much of California, has been known to cause death when its roots are eaten like wild carrots or parsnips. Giant Hogweed, which is more prevalent in the Pacific Northwest, Canada and the eastern U.S., produces a toxic sap that can cause skin irritation and blindness.