Flower profile

Lambert's locoweed

Oxytropis lambertii

Native in the lower 48

Lambert's locoweed is a wildflower that USDA PLANTS lists as native in the lower 48 states. It's on our flower lists for 4 states, and across the U.S. it's most often seen in bloom in May–August.

15states

4of our state lists

6,933U.S. sightings*

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

On our lists for: Colorado, Nebraska, North Dakota, South Dakota

Quick look

Oxytropis lambertii commonly known as purple locoweed, Colorado locoweed, Lambert's crazy weed, or Lambert’s Locoweed is a species of flowering plant in the legume family.
From Wikipedia's article Oxytropis lambertii, CC BY-SA 4.0.

It belongs to the Fabaceae 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 15 states. ^{USDA PLANTS}
NatureServe lists it as native to Colorado, North Dakota, South Dakota and Nebraska. ^NatureServe
In Colorado, most iNaturalist sightings of it in flower come in May–July. ^iNaturalist
In North Dakota, most iNaturalist sightings of it in flower come in May–July. ^iNaturalist
USDA PLANTS lists its flower color as red. ^{USDA PLANTS}
USDA PLANTS gives its bloom period as mid spring. ^{USDA PLANTS}
USDA PLANTS lists a mature height of about 1.4 ft. ^{USDA PLANTS}
iNaturalist has 3,838 research-grade sightings of it in Colorado, ranking #30 among the 110 flowers on our Colorado list. ^iNaturalist
iNaturalist has 343 research-grade sightings of it in North Dakota, ranking #12 among the 109 flowers on our North Dakota list. ^iNaturalist
iNaturalist has 262 research-grade sightings of it in South Dakota, ranking #52 among the 108 flowers on our South Dakota list. ^iNaturalist

Lambert's locoweed gift ideas

Handmade lambert's locoweed gifts from independent makers.

🌱 Sample spot. Handmade gift picks from independent shops will appear here once our shop partnership is approved. These cards are placeholders, not real products.

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Lambert's locoweed art print
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Lambert's locoweed greeting card
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Lambert's locoweed mug
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Lambert's locoweed earrings
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Lambert's locoweed embroidery pattern
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Lambert's locoweed sticker
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When does it bloom?

Flowering records by month across the U.S. (iNaturalist research-grade observations marked “Flowering”) (354 records)

Bloom time in each of our 4 states

State	Type	Peak bloom	Sightings*
Colorado	Native	May–July	3,838
North Dakota	Native	May–July	343
South Dakota	Native	few records	262
Nebraska	Native	few records	165

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
Colorado: No list Colorado has no state law listing endangered or threatened plants, so we show NatureServe's Colorado ranks instead. NatureServe: S5, secure in Colorado.
North Dakota: No list North Dakota has no state law listing endangered or threatened plants, so we show NatureServe's North Dakota ranks instead. NatureServe: SNR, not yet ranked in North Dakota.
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.
Nebraska: Not listed Not on Nebraska threatened and endangered species (163 Neb. Admin. Code ch. 4, § 004). NatureServe: SNR, not yet ranked in Nebraska. ^{163 NAC 4-004}
Rare elsewhere: No other U.S. state ranks it S1, S2, SH or SX.

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

Can you eat it?

For peopleToxic (severe, per USDA)

USDA PLANTS rates its toxicity as “severe.” (USDA's rating covers people and livestock and doesn't say which parts.) NC State Extension has no page for it. ^{USDA PLANTS}

For petsToxic to horses (not dogs or cats)

ASPCA's entry “Loco Weed (Oxytropis spp.)” (Oxytropis spp), which covers the whole genus, lists it as toxic to horses, but non-toxic to dogs and cats. Signs include: Incoordination, depression, inability to eat and drink, fetal death and birth defects Credit: Image Courtesy of Gary Coffman, PBase.com Gallery… ^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 lambert's locoweed in 15 states.

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recorded by USDA PLANTS on our state lists not recorded

See the full list of states

Arizona, Colorado, Iowa, Kansas, Minnesota, Missouri, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, Utah, Wyoming.

Colorado counties with USDA records: Adams, Alamosa, Arapahoe, Baca, Boulder, Clear Creek, Conejos, Custer, Denver, Dolores, Douglas, El Paso, Elbert, Fremont, Garfield, Gilpin, Grand, Gunnison, Huerfano, Jackson, Jefferson, Kiowa, Kit Carson, Lake, Larimer, Las Animas, Logan, Mesa, Mineral, Park, Phillips, Pueblo, Rio Blanco, Rio Grande, Routt, Saguache, Sedgwick, Teller, Weld, Yuma.

North Dakota counties with USDA records: Adams, Barnes, Benson, Billings, Bottineau, Bowman, Burke, Burleigh, Cass, Dickey, Divide, Dunn, Emmons, Golden Valley, Grand Forks, Grant, Hettinger, Kidder, LaMoure, McHenry, McIntosh, McKenzie, McLean, Mercer, Morton, Mountrail, Oliver, Pierce, Ramsey, Ransom, Renville, Richland, Sargent, Sioux, Slope, Stark, Stutsman, Ward, Wells, Williams.

South Dakota counties with USDA records: Aurora, Bennett, Bon Homme, Brown, Brule, Butte, Charles Mix, Clay, Corson, Custer, Davison, Dewey, Edmunds, Fall River, Faulk, Grant, Gregory, Haakon, Hanson, Harding, Hughes, Hutchinson, Hyde, Jackson, Jerauld, Lawrence, Lincoln, Lyman, McCook, Meade, Mellette, Minnehaha, Pennington, Stanley, Todd, Tripp, Turner, Union, Walworth, Yankton, Ziebach.

More Colorado flowers

White clover

Trifolium repens

Introduced

🌼 Blooms: March–September

Red clover

Trifolium pratense

★ VT state flowerIntroduced

🌼 Blooms in CO: June–October

Eastern redbud

Cercis canadensis

Native

🌼 Blooms: February–May

Sources

USDA, NRCS. PLANTS Database, profile OXLA3.
iNaturalist, Oxytropis lambertii: taxonomy, research-grade observation counts and “Flowering” annotations, retrieved October 17, 2026.
Wikipedia, Oxytropis lambertii (lead quoted under CC BY-SA 4.0).
Colorado: Colorado noxious weed lists A, B and C (8 CCR 1206-2, eff. May 15, 2025).
North Dakota: North Dakota state noxious weeds (N.D. Admin. Code 7-06-01-02), as listed by the ND Department of Agriculture.
South Dakota: South Dakota statewide noxious weeds (ARSD 12:62:03:01.06).
Nebraska: Nebraska threatened and endangered species (163 Neb. Admin. Code ch. 4, § 004).
Nebraska: Nebraska noxious weeds (25 Neb. Admin. Code ch. 10, § 001.02).
USFWS, ECOS species database (ESA listing check), October 17, 2026.
NatureServe Explorer, Oxytropis lambertii (global and state ranks).
Edibility and toxicity: USDA PLANTS; ASPCA.
Photo: Larry Jensen via iNaturalist · CC BY 4.0 · resized.