Cow parsnip

My continuing investigations into invasive plants take me further and further afield (so to speak), today to Bay Area wildflowers, of which there are a great many — some shy woodland flowers, some small plants that (in their season) blanket hillsides and meadows, and some weedy and imposing plants. Now a web list of area wildflowers turns up many familiar plants from my days of wildflower tracking, including a giant, the cow parsnip:


(Note the big white umbels and the huge celery-like leaves.)

From Wikipedia:

Heracleum maximum, cow parsnip (also known as Indian celery, Indian rhubarb or pushki) is the only member of the genus Heracleum native to North America [other species in the genus are introduced plants]. … 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 about 9000 ft, and is especially prevalent in Alaska. It is listed as “Endangered” in Kentucky and “Special Concern” in Tennessee. In Canada, it is found in each province and territory, except Nunavut. It may be weedy or invasive in portions of its range.

Note that the very same plant can be threatened in some places and rampant in others.

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.

Thirty-some years ago I had the experience of walking within a stand of cow parsnip, towering over me, at Point Reyes, north of here in California.

Two further things about cow parsnip: its classification, and its hazardous similarity to some other plants of the carrot / celery family.

Naming. More from Wikipedia:

Its classification has caused some difficulty, with recent authoritative sources referring to it variously as Heracleum maximum or Heracleum lanatum, or as either a subspecies, H. sphondylium subsp. montanum, or a variety, H. sphondylium var. lanatum, of the common hogweed (H. sphondylium). The classification given here follows ITIS.

From the ITIS site:

Welcome to ITIS, the Integrated Taxonomic Information System! Here you will find authoritative taxonomic information on plants, animals, fungi, and microbes of North America and the world. We are a partnership of U.S., Canadian, and Mexican agencies; other organizations; and taxonomic specialists.

Similar species, These are all Apiaceae.

The water parsnip (Sium suave), western water hemlock (Cicuta douglasii), and spotted water hemlock (Cicuta maculata) all have white flowers in large compound umbels and therefore are easily confused with cow parsnip. … All water hemlock is highly poisonous [like Conium maculatum, the poison hemlock of Socrates fame]. Water parsnip [like cow parsnip] is not poisonous.

The Wikipedia section goes on to provide helpful pointers for distinguishing the poisonous hemlocks from the edible parsnips (note that the culinary parsnip, Pastinaca sativa, is also in the Apiaceae, though it’s a much more modest plant than the ones listed above).

Bonus. And then there’s Anthriscus sylvestris, known as cow parsley, wild chervil (culinary chervil is Anthriscus cerefolium), wild carrot, or Queen Anne’s lace, also in the Apiaceae, and not poisonous. But tending to be invasive. From Wikipedia:

Cow parsley grows in sunny to semi-shaded locations in meadows and at the edges of hedgerows and woodland. It is a particularly common sight by the roadside. It is sufficiently common and fast-growing to be considered a nuisance weed in gardens. Cow parsley’s ability to grow rapidly through rhizomes and to produce large quantities of seeds in a single growing season has made it an invasive species in many areas of the United States. (Vermont has listed cow parsley on its “Watch List” of invasive species, while Massachusetts and Washington have banned the sale of the plant.)


There are reports that in the U.K., cow parsley has been aggressively overwhelming other roadside plants.

Finally, there’s fool’s parsley, which you’ll want to avoid:

Aethusa cynapium (fool’s parsley, fool’s cicely [Myrrhis odorata, (sweet) cicely, is a plant in the Apiaceae sometimes used as an herb], or poison parsley) is an annual (rarely biennial) herb in the plant family Apiaceae, native to Europe, western Asia, and northwest Africa. It is the only member of the genus Aethusa. It is related to Hemlock and Water-dropwort, and like them it is poisonous, though less so than hemlock. It has been introduced into many other parts of the world and is a common weed in cultivated ground. (Wikipedia link)

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