Flower profile

Sulfur buckwheat

Eriogonum umbellatum

Sulfur buckwheat (Eriogonum umbellatum) is a shrub in the Polygonaceae family, native in the lower 48 states, blooming mostly June–August across the U.S.

Native in the lower 48

Sulfur buckwheat 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 June–August.

10states where USDA records it

4Bloomipedia state lists include it

18,137U.S. sightings*

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

On our lists for: Colorado, Idaho, Nevada, Wyoming

Quick look

Eriogonum umbellatum is a species of wild buckwheat known by the common name sulphurflower buckwheat, or simply sulphur flower.
From Wikipedia's article Eriogonum umbellatum, CC BY-SA 4.0.

It belongs to the Polygonaceae family. ^iNaturalist
USDA PLANTS describes it as an herb (forb) / a shrub with a perennial life cycle. ^{USDA PLANTS}
USDA PLANTS lists it as native in the lower 48 states and records it in 10 states. ^{USDA PLANTS}
NatureServe lists it as native to Colorado, Wyoming, Nevada and Idaho. ^NatureServe
In Colorado, most iNaturalist sightings of it in flower come in June–July. ^iNaturalist
In Wyoming, most iNaturalist sightings of it in flower come in June–August. ^iNaturalist
USDA PLANTS lists its flower color as yellow. ^{USDA PLANTS}
USDA PLANTS gives its bloom period as early summer. ^{USDA PLANTS}
USDA PLANTS lists a mature height of about 1 ft. ^{USDA PLANTS}
iNaturalist has 6,111 research-grade sightings of it in Colorado, ranking #11 among the 160 flowers on our Colorado list. ^iNaturalist
iNaturalist has 1,999 research-grade sightings of it in Wyoming, ranking #4 among the 113 flowers on our Wyoming list. ^iNaturalist
iNaturalist has 1,174 research-grade sightings of it in Nevada, ranking #24 among the 132 flowers on our Nevada list. ^iNaturalist

When does it bloom?

Flowering records by month across the U.S. (iNaturalist research-grade observations marked “Flowering”) (2,400 records)

Bloom time in the 4 states whose Bloomipedia list includes it

State	Type	Peak bloom	Sightings*
Colorado	Native	June–July	6,111
Wyoming	Native	June–August	1,999
Nevada	Native	June–August	1,174
Idaho	Native	few records (28)	486

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.
Wyoming: No list Wyoming has no state law listing endangered or threatened plants, so we show NatureServe's Wyoming ranks instead. NatureServe: S5, secure in Wyoming.
Nevada: Not listed Not on Nevada fully protected plants, critically endangered (NAC 527.010). NatureServe: S5, secure in Nevada. ^{NAC 527.010}
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.
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 peopleNot well documented

None of the sources we checked (NC State Extension (no edibility or poison notes on its page), USDA PLANTS) say whether it's edible or poisonous for people. ^{NC State Extension}

For petsNot well documented

It isn't on the ASPCA plant list, and NC State Extension doesn't flag it for pets.

🌿 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 sulfur buckwheat in 10 states.

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recorded by USDA PLANTS on our state lists not recorded

See the full list of states

Arizona, California, Colorado, Idaho, Montana, Nevada, Oregon, Utah, Washington, Wyoming.

Colorado counties with USDA records: Arapahoe, Boulder, Clear Creek, Costilla, Custer, Delta, Dolores, Douglas, Eagle, El Paso, Garfield, Gilpin, Grand, Gunnison, Jackson, Jefferson, La Plata, Lake, Larimer, Mesa, Moffat, Montezuma, Montrose, Park, Pitkin, Rio Blanco, Routt, Saguache, San Miguel, Summit.

Wyoming counties with USDA records: Albany, Big Horn, Campbell, Carbon, Converse, Fremont, Hot Springs, Johnson, Laramie, Lincoln, Natrona, Park, Sheridan, Sublette, Sweetwater, Teton, Uinta, Washakie.

Nevada counties with USDA records: Carson City, Churchill, Clark, Douglas, Elko, Esmeralda, Eureka, Humboldt, Lander, Lincoln, Lyon, Mineral, Nye, Pershing, Storey, Washoe, White Pine.

Growing conditions

USDA PLANTS gives Sulfur buckwheat a high shade tolerance, high drought tolerance and low moisture use. It is rated for soil pH 6.5 to 8.0 and winter lows down to -13 °F.

Shade tolerance: High
Drought tolerance: High
Moisture use: Low
Soil textures it is adapted to: coarse, medium
Soil pH range: 6.5 to 8.0
Minimum temperature tolerated: -13 °F
Frost-free days needed (minimum): 140
Annual precipitation range: 14 to 18 inches
Minimum root depth: 20 inches
Salinity tolerance: High
Fertility requirement: Low
Growth rate: Slow
Lifespan: Long
Active growth period: Spring and Summer
Fruit or seed: Brown · Summer to Fall
Can be propagated by: bare root, container, seed
Commercial availability: Routinely Available

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

Names, range and relatives

Native status by region (USDA PLANTS): Canada: Native; Lower 48 states: Native.

County records: USDA PLANTS lists it in 237 counties across 10 states; the most are in California (44), Montana (32), Idaho (31).

Other Eriogonum on Bloomipedia (9): California buckwheat, Desert trumpet, Cushion buckwheat, Parsnipflower buckwheat, Redroot buckwheat, James' buckwheat, Alpine golden buckwheat, Annual buckwheat, Few-flower buckwheat.

More from the Polygonaceae family (21 on Bloomipedia; most observed first): American jumpseed, Low smartweed, Japanese knotweed, Mile-a-minute weed, Water smartweed, American bistort, Spotted lady's thumb, Devil's spineflower.

More Colorado flowers

American bistort

Bistorta bistortoides

Native

🌼 Blooms in CO: June–August

Great mullein

Verbascum thapsus

Introduced

🌼 Blooms in CO: July–October

Blue columbine

Aquilegia coerulea

★ CO state flowerNative

🌼 Blooms in CO: June–August

Sources

USDA, NRCS. PLANTS Database, profile ERUM.
iNaturalist, Eriogonum umbellatum: taxonomy, research-grade observation counts and “Flowering” annotations, retrieved October 17, 2026.
Wikipedia, Eriogonum umbellatum (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).
Wyoming: Wyoming state designated noxious weeds (W.S. 11-5-102(a)(xi)), as listed by the Wyoming Weed & Pest Council.
Nevada: Nevada fully protected plants, critically endangered (NAC 527.010).
Nevada: Nevada noxious weeds (NAC 555.010).
Idaho: Idaho noxious weeds (IDAPA 02.06.09, Section 220).
USFWS, ECOS species database (ESA listing check), October 17, 2026.
NatureServe Explorer, Eriogonum umbellatum (global and state ranks).
Edibility and toxicity: NC State Extension.
Photo: Daughter Dad via iNaturalist · CC BY 4.0 · resized.