Flower profile

Common cowparsnip

Heracleum maximum

Common cowparsnip (Heracleum maximum) is a flowering plant in the Apiaceae family, native in the lower 48 states, blooming mostly May–July across the U.S.

Native in the lower 48

Common cowparsnip is a wildflower that USDA PLANTS lists as native in the lower 48 states. It's on our flower lists for 14 states, and across the U.S. it's most often seen in bloom in May–July.

41states where USDA records it

14Bloomipedia state lists include it

45,338U.S. sightings*

*iNaturalist research-grade observations, as of October 17, 2026.

On our lists for: Alaska, California, Colorado, Idaho, Illinois, Michigan, Minnesota, Montana, Oregon, South Dakota, Utah, Washington, Wisconsin, Wyoming

Quick look

Heracleum maximum, commonly known as cow parsnip, is the only member of the genus Heracleum native to North America. It is also known as American cow-parsnip, Satan celery, Indian celery, Indian rhubarb, poison turnip or pushki.
From Wikipedia's article Heracleum maximum, CC BY-SA 4.0.

It belongs to the Apiaceae family. ^iNaturalist
USDA PLANTS describes it as an herb (forb) with a perennial life cycle. ^{USDA PLANTS}
USDA PLANTS lists it as native in the lower 48 states and records it in 41 states. ^{USDA PLANTS}
In California, most iNaturalist sightings of it in flower come in April–July. ^iNaturalist
In Oregon, most iNaturalist sightings of it in flower come in May–June. ^iNaturalist
USDA PLANTS lists its flower color as white. ^{USDA PLANTS}
USDA PLANTS gives its bloom period as early summer. ^{USDA PLANTS}
USDA PLANTS lists a mature height of about 8 ft. ^{USDA PLANTS}
iNaturalist has 12,397 research-grade sightings of it in California, ranking #67 among the 178 flowers on our California list. ^iNaturalist
iNaturalist has 5,131 research-grade sightings of it in Oregon, ranking #18 among the 184 flowers on our Oregon list. ^iNaturalist
iNaturalist has 3,766 research-grade sightings of it in Colorado, ranking #31 among the 160 flowers on our Colorado list. ^iNaturalist

When does it bloom?

Flowering records by month across the U.S. (iNaturalist research-grade observations marked “Flowering”) (2,461 records)

Bloom time in the 14 states whose Bloomipedia list includes it

State	Type	Peak bloom	Sightings*
California	Native	April–July	12,397
Oregon	Native	May–June	5,131
Colorado	Native	June–August	3,766
Alaska	Native	June–July	3,655
Washington	Native	May–July	3,461
Wisconsin	Native	May–June	1,977
Illinois	Native	May–June	1,967
Michigan	Native	May–July	1,636
Minnesota	Native	few records (43)	1,557
Montana	Native	few records (30)	1,259
Wyoming	Native	few records (32)	947
Utah	Native	June–August	652
Idaho	Native	few records (13)	523
South Dakota	Native	few records (11)	281

Conservation status

Federal (U.S. ESA)

Not listed No U.S. Endangered Species Act listing in the USFWS ECOS database. ^{USFWS ECOS}

NatureServe global

G5 Secure worldwide. ^NatureServe

State rare plant lists

Not listed Not on the official rare plant list in 6 of our 14 states.

See each state

California: Not listed Not on California state-listed endangered, threatened and rare plants (14 CCR § 670.2), per CDFW's CNDDB list (July 2026). NatureServe: SNR, not yet ranked in California. ^{CNDDB listed plants (July 2026)}
Oregon: Not listed Not on Oregon endangered and threatened plants (OAR 603-073-0070). NatureServe: SNR, not yet ranked in Oregon. ^{OAR 603-073-0070}
Wisconsin: Not listed Not on Wisconsin endangered and threatened species list (Wis. Admin. Code NR 27.03). NatureServe: SNR, not yet ranked in Wisconsin. ^{NR 27.03}
Illinois: Not listed Not on Illinois List of Endangered and Threatened Flora (17 Ill. Adm. Code 1050), per the Endangered Species Protection Board's 2025 checklist. NatureServe: SNR, not yet ranked in Illinois. ^{IL E&T checklist 2025}
Michigan: Not listed Not on Michigan endangered and threatened plants (Mich. Admin. Code R 299.1028, eff. March 20, 2023). NatureServe: SNR, not yet ranked in Michigan. ^{R 299.1028}
Minnesota: Not listed Not on Minnesota endangered, threatened and special concern plants (Minn. R. 6134.0300). NatureServe: SNR, not yet ranked in Minnesota. ^{Minn. R. 6134.0300}

Colorado

No list Colorado has no state law listing endangered or threatened plants, so we show NatureServe's Colorado ranks instead. NatureServe: S4, apparently secure in Colorado.

Alaska

No list Alaska has no state law listing endangered or threatened plants, so we show NatureServe's Alaska ranks instead. NatureServe: SNR, not yet ranked in Alaska.

Washington

No list Washington has no state law listing endangered or threatened plants (the Washington Natural Heritage Program's rare plant list isn't regulatory), so we show NatureServe's Washington ranks instead. NatureServe: SNR, not yet ranked in Washington.

Montana

No list Montana has no state law listing endangered or threatened plants, so we show NatureServe's Montana ranks instead. NatureServe: S4, apparently secure in Montana.

Wyoming

No list Wyoming has no state law listing endangered or threatened plants, so we show NatureServe's Wyoming ranks instead. NatureServe: S4, apparently secure in Wyoming.

Utah

No list Utah has no state law listing endangered or threatened plants, so we show NatureServe's Utah ranks instead. NatureServe: SNR, not yet ranked in Utah.

Idaho

No list Idaho has no state law listing endangered or threatened plants, so we show NatureServe's Idaho ranks instead. NatureServe: SNR, not yet ranked in Idaho.

South Dakota

No list South Dakota's endangered and threatened list (ARSD 41:10:02) covers animals only, so we show NatureServe's South Dakota ranks for plants. NatureServe: SNR, not yet ranked in South Dakota.

Rare elsewhere

Other states where NatureServe ranks it rare or missing: GA (S1), KS (S1), KY (S1), TN (S2). (S1 critically imperiled, S2 imperiled, SH possibly extirpated, SX presumed extirpated.)

Checked October 17, 2026. Rankings and lists can change, so follow the links for the latest.

Can you eat it?

For peopleCaution: partly edible, partly poisonous

NC State Extension lists it as poisonous to humans (severity: low). Poisonous parts: sap/juice. Symptoms they list: “Photosensitization (sunburn, dermatitis), eye irritation upon exposure to the sap, and subsequent exposure to sunlight.” They also note: “Young stems can be peeled, cooked and eaten. Roots can be cooked and eaten like parsnip.” ^{NC State Extension}

For petsToxic to dogs, cats and horses

ASPCA's entry “Cow parsnip” (Heracleum maximum) lists it as toxic to dogs, cats and horses. Signs include: Photosensitization (sunburn… ^ASPCA

🌿 Never eat a wild plant unless you're certain of its ID; this isn't medical advice. Worried about a person? Call Poison Control at 1-800-222-1222. Worried about a pet? Call your vet.

Where does it grow?

USDA PLANTS records common cowparsnip in 41 states.

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recorded by USDA PLANTS on our state lists not recorded

See the full list of states

Alaska, Arizona, California, Colorado, Connecticut, Delaware, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Dakota, Tennessee, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, Wyoming.

California counties with USDA records: Alameda, Alpine, Butte, Colusa, Contra Costa, El Dorado, Fresno, Glenn, Humboldt, Inyo, Lake, Madera, Marin, Mariposa, Mendocino, Modoc, Mono, Monterey, Napa, Nevada, Placer, Plumas, San Bernardino, San Francisco, San Luis Obispo, San Mateo, Santa Clara, Santa Cruz, Shasta, Siskiyou, Sonoma, Trinity, Tulare, Tuolumne.

Oregon counties with USDA records: Baker, Benton, Clackamas, Clatsop, Columbia, Coos, Crook, Curry, Deschutes, Douglas, Grant, Harney, Hood River, Jackson, Jefferson, Josephine, Klamath, Lake, Lane, Lincoln, Linn, Malheur, Marion, Morrow, Multnomah, Polk, Tillamook, Umatilla, Union, Wallowa, Wasco, Washington, Wheeler, Yamhill.

Colorado counties with USDA records: Alamosa, Boulder, Custer, Denver, Douglas, Eagle, El Paso, Garfield, Gilpin, Grand, Gunnison, Huerfano, Jefferson, La Plata, Larimer, Las Animas, Mesa, Montrose, Park, Pitkin, Pueblo, Rio Blanco, Routt, Saguache, San Juan, San Miguel, Teller.

Growing conditions

USDA PLANTS gives Common cowparsnip a high shade tolerance, low drought tolerance and high moisture use. It is rated for soil pH 5.4 to 7.3 and winter lows down to -38 °F.

Shade tolerance: High
Drought tolerance: Low
Moisture use: High
Soil textures it is adapted to: coarse, medium, fine
Soil pH range: 5.4 to 7.3
Minimum temperature tolerated: -38 °F
Frost-free days needed (minimum): 110
Annual precipitation range: 14 to 45 inches
Minimum root depth: 12 inches
Salinity tolerance: None
Fertility requirement: Medium
Growth rate: Moderate
Lifespan: Short
Active growth period: Spring and Summer
Fruit or seed: Brown · Summer to Summer
Can be propagated by: seed
Commercial availability: Routinely Available

From the USDA PLANTS characteristics data for HEMA80. USDA ratings are general guidance for the species, not a guarantee for your garden.

Names, range and relatives

Native status by region (USDA PLANTS): Alaska: Native; Canada: Native; Lower 48 states: Native; St. Pierre and Miquelon: Native.

Other scientific names (synonyms in USDA PLANTS): Heracleum lanatum.

County records: USDA PLANTS lists it in 765 counties across 38 states; the most are in Minnesota (58), Illinois (55), Wisconsin (47).

More from the Apiaceae family (16 on Bloomipedia; most observed first): Queen Anne's lace (wild carrot), Poison hemlock, Common hedge parsley, Fennel, Rattlesnake master, Golden alexanders, Goutweed, Aniseroot.

More California flowers

Fennel

Foeniculum vulgare

Introduced

🌼 Blooms in CA: June–September

Poison hemlock

Conium maculatum

Introduced

🌼 Blooms in CA: April–June

California poppy

Eschscholzia californica

★ CA state flowerNative

🌼 Blooms in CA: March–May

Sources

USDA, NRCS. PLANTS Database, profile HEMA80.
iNaturalist, Heracleum maximum: taxonomy, research-grade observation counts and “Flowering” annotations, retrieved October 17, 2026.
Wikipedia, Heracleum maximum (lead quoted under CC BY-SA 4.0).
State rare and invasive plant lists (20):
Show all 20 state lists
USFWS, ECOS species database (ESA listing check), October 17, 2026.
NatureServe Explorer, Heracleum maximum (global and state ranks).
Edibility and toxicity: NC State Extension; ASPCA.
Photo: Tom Scavo via iNaturalist · CC BY 4.0 · resized.