[The Genus Heracleum East of the Cascade Mts. of Oregon and Washington]

Cow Parsnip, Cow-parsnip, Common Cow-parsnip, American Cow-parsnip

Heracleum maximum

Synonyms: Heracleum douglasii, Heracleum lanatum, Heracleum sphondylium ssp. montanum, Heracleum sphondylium var. lanatum, Pastinaca lanatum

Cow Parsnip, Cow-parsnip, Common Cow-parsnip, American Cow-parsnip: Heracleum maximum (Synonyms: Heracleum douglasii, Heracleum lanatum, Heracleum sphondylium ssp. montanum, Heracleum sphondylium var. lanatum, Pastinaca lanatum) - Cow Parsnip, Cow-parsnip, Common Cow-parsnip, American Cow-parsnip: Heracleum maximum (Synonyms: Heracleum douglasii, Heracleum lanatum, Heracleum sphondylium ssp. montanum, Heracleum sphondylium var. lanatum, Pastinaca lanatum)

The photo at left shows the large leaves and umbels of cow parsnip as seen on weedy grass infested slopes at the base of Steptoe Butte in the Palouse country of eastern Washington........June 22, 2009. Note the large, inflated bases to the leaf petioles and the numerous white, spreading hairs on the stems. The photo at right shows cow parsnip in bloom along the Switchback Trail just north of several different parcels of private property. This wet area is on WDFW lands surrounding Waikiki Springs, Spokane County, WA.....June 24, 2022.
Characteristics:

Cow parsnip is a large, fairly attractive perennial wildflower with a single, stout and erect stem from one to three meters high. The lower stems may be lightly haired, but the underside of the leaves and upper stems near the inflorescence are thinly tomentose to woolly-villous. The stems are hollow and heavily veined. The large leaves are once-ternate with broad petiolate leaflets which are palmately veined with coarsely toothed margins. The blades of the leaflets are roughly 10-30 cm long and about as wide, with the central leaflet the largest.

The inflorescence is a compound umbel (See photo below.) with 10-30 unequal rays, each from 5-10 cm long. 5-10 narrow, deciduous bracts are found at the base of the umbel as well as at the base of the individual umbellets. The flowers are white, with the outer flowers of the outer umbellets having large, deeply obcordate petals. The fruit are broadly elliptic to obovate in shape with a notch at the apex, and range from 8-12 mm long and 7-9 mm wide. Cow Parsnip is a prolific self-seeder and easily establishes itself in the moist, shady garden.

Habitat:

Cow parsnip is found along streambanks and on moist ground in shady woods.

Range:

Cow parsnip is found from Alaska south to California and Arizona and east to Newfoundland and hence south to Georgia. It is also found in Siberia and the Kurile Islands.

Cow Parsnip, Cow-parsnip, Common Cow-parsnip, American Cow-parsnip: Heracleum maximum (Synonyms: Heracleum douglasii, Heracleum lanatum, Heracleum sphondylium ssp. montanum, Heracleum sphondylium var. lanatum, Pastinaca lanatum) - Umbel of Cow Parsnip, Cow-parsnip, Common Cow-parsnip, American Cow-parsnip: Heracleum maximum (Synonyms: Heracleum douglasii, Heracleum lanatum, Heracleum sphondylium ssp. montanum, Heracleum sphondylium var. lanatum, Pastinaca lanatum)

Views of the whole plant and habitat as well as a close-up view from above of the umbel of cow parsnip as seen at Steptoe Butte in eastern Washington..........June 22, 2009. Each umbel is shaped like a nearly flat-topped umbrella with numerous rays of equal to more often irregular length capped by a smaller umbel of flowers. This smaller umbel is known as an umbellet.

Umbellet of Cow Parsnip, Cow-parsnip, Common Cow-parsnip, American Cow-parsnip: Heracleum maximum (Synonyms: Heracleum douglasii, Heracleum lanatum, Heracleum sphondylium ssp. montanum, Heracleum sphondylium var. lanatum, Pastinaca lanatum) - Underside view of an umbellet of Cow Parsnip, Cow-parsnip, Common Cow-parsnip, American Cow-parsnip: Heracleum maximum (Synonyms: Heracleum douglasii, Heracleum lanatum, Heracleum sphondylium ssp. montanum, Heracleum sphondylium var. lanatum, Pastinaca lanatum) - Fruits of Cow Parsnip, Cow-parsnip, Common Cow-parsnip, American Cow-parsnip: Heracleum maximum (Synonyms: Heracleum douglasii, Heracleum lanatum, Heracleum sphondylium ssp. montanum, Heracleum sphondylium var. lanatum, Pastinaca lanatum)

Close-ups of views of the upper (left) and underside surfaces(middle) of an umbellet as well as the developing fruits (right) of cow parsnip as seen at Steptoe Butte in eastern Washington.........June 22, 2009. Note the long, linear-shaped bracts at the base of each umbellet. These secondary bracts of the umbellet are known as the involucel.

Seeds of Cow Parsnip, Cow-parsnip, Common Cow-parsnip, American Cow-parsnip: Heracleum maximum (Synonyms: Heracleum douglasii, Heracleum lanatum, Heracleum sphondylium ssp. montanum, Heracleum sphondylium var. lanatum, Pastinaca lanatum)

Fruits of cow parsnip.

Umbel of Cow Parsnip, Cow-parsnip, Common Cow-parsnip, American Cow-parsnip: Heracleum maximum (Synonyms: Heracleum douglasii, Heracleum lanatum, Heracleum sphondylium ssp. montanum, Heracleum sphondylium var. lanatum, Pastinaca lanatum) - Cow Parsnip, Cow-parsnip, Common Cow-parsnip, American Cow-parsnip: Heracleum maximum (Synonyms: Heracleum douglasii, Heracleum lanatum, Heracleum sphondylium ssp. montanum, Heracleum sphondylium var. lanatum, Pastinaca lanatum)

Cow parsnip in bloom along the Maxwell Lake Trail in moist areas near Lostine Creek, Eagle Creek Wilderness..........August 3, 2016.

Cow Parsnip, Cow-parsnip, Common Cow-parsnip, American Cow-parsnip: Heracleum maximum (Synonyms: Heracleum douglasii, Heracleum lanatum, Heracleum sphondylium ssp. montanum, Heracleum sphondylium var. lanatum, Pastinaca lanatum)

Cow parsnip seen in moist springs along the Roads End Trail, Strawberry Mountain Wilderness.........August 19, 2011.

Cow Parsnip, Cow-parsnip, Common Cow-parsnip, American Cow-parsnip: Heracleum maximum (Synonyms: Heracleum douglasii, Heracleum lanatum, Heracleum sphondylium ssp. montanum, Heracleum sphondylium var. lanatum, Pastinaca lanatum)

Cow parsnip as seen in wetlands near the P Ranch, Malheur NWR, southeastern Oregon.
Paul Slichter