Bloomipedia
Curveseed butterwort (Ceratocephala testiculata)
Photo: Daughter Dad via iNaturalist · CC BY 4.0 · resized

Flower profile

Curveseed butterwort

Ceratocephala testiculata

Curveseed butterwort (Ceratocephala testiculata) is a flowering plant in the Ranunculaceae family, introduced in the lower 48 states, blooming mostly March–April across the U.S.

Introduced in the lower 48

Curveseed butterwort is a wildflower that USDA PLANTS lists as introduced in the lower 48 states. It's on our flower lists for 3 states, and across the U.S. it's most often seen in bloom in March–April.

23states where USDA records it
3Bloomipedia state lists include it
3,555U.S. sightings*

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

On our lists for: Idaho, Nevada, Utah

Quick look

Ceratocephala testiculata is a flowering plant that is native to Eurasia. Common names include bur buttercup and curveseed butterwort. It is very small, usually only about an inch or two tall, but potentially growing to four inches. The flowers are small and dull yellow. The leaves are hairy and somewhat dissected. It produces a cluster of hard, spiny fruits.

  • It belongs to the Ranunculaceae family. iNaturalist
  • USDA PLANTS describes it as an herb (forb) with a annual life cycle. USDA PLANTS
  • USDA PLANTS lists it as introduced in the lower 48 states and records it in 23 states. USDA PLANTS
  • NatureServe lists it as not native to Utah, Idaho and Nevada. NatureServe
  • In Utah, most iNaturalist sightings of it in flower come in March–April. iNaturalist
  • iNaturalist has 946 research-grade sightings of it in Utah, ranking #60 among the 153 flowers on our Utah list. iNaturalist
  • iNaturalist has 511 research-grade sightings of it in Idaho, ranking #63 among the 143 flowers on our Idaho list. iNaturalist
  • iNaturalist has 408 research-grade sightings of it in Nevada, ranking #101 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”) (301 records)
Bloom time in the 3 states whose Bloomipedia list includes it
StateTypePeak bloomSightings*
UtahIntroducedMarch–April946
IdahoIntroducedfew records (34)511
NevadaIntroducedfew records (16)408

Conservation status

Federal (U.S. ESA)
Not listed No U.S. Endangered Species Act listing in the USFWS ECOS database. USFWS ECOS
NatureServe global
GNR Not yet ranked worldwide. NatureServe
Utah
No list Utah has no state law listing endangered or threatened plants, so we show NatureServe's Utah ranks instead. NatureServe: SNA, not applicable (usually because it isn't native there) in Utah.
Idaho
No list Idaho has no state law listing endangered or threatened plants, so we show NatureServe's Idaho ranks instead. NatureServe: SNA, not applicable (usually because it isn't native there) in Idaho.
Nevada
Not listed Not on Nevada fully protected plants, critically endangered (NAC 527.010). NatureServe: SNA, not applicable (usually because it isn't native there) in Nevada. NAC 527.010
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 page for this plant), USDA PLANTS) say whether it's edible or poisonous for people.

For petsNot well documented

It isn't on the ASPCA plant list.

🌿 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 curveseed butterwort in 23 states.

recorded by USDA PLANTS on our state lists not recorded

See the full list of states

Arizona, California, Colorado, Idaho, Illinois, Indiana, Iowa, Kansas, Minnesota, Missouri, Montana, Nebraska, Nevada, New Mexico, New York, North Dakota, Ohio, Oregon, South Dakota, Utah, Washington, Wisconsin, Wyoming.

Utah counties with USDA records: Beaver, Box Elder, Cache, Carbon, Daggett, Davis, Duchesne, Emery, Garfield, Grand, Iron, Juab, Kane, Millard, Morgan, Piute, Rich, Salt Lake, San Juan, Sanpete, Sevier, Summit, Tooele, Uintah, Utah, Wasatch, Washington, Wayne, Weber.

Idaho counties with USDA records: Ada, Adams, Bannock, Bear Lake, Bingham, Blaine, Bonneville, Butte, Camas, Canyon, Cassia, Clark, Elmore, Gem, Gooding, Idaho, Latah, Lemhi, Lewis, Lincoln, Nez Perce, Oneida, Owyhee, Payette, Power, Teton, Twin Falls, Washington.

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

Names, range and relatives

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

Other scientific names (synonyms in USDA PLANTS): Ceratocephala orthoceras, Ranunculus testiculatus.

County records: USDA PLANTS lists it in 158 counties across 16 states; the most are in Utah (29), Idaho (28), Oregon (19).

More from the Ranunculaceae family (48 on Bloomipedia; most observed first): Lesser celandine, Rue anemone, Red columbine, Wood anemone, Western columbine, Marsh marigold, White baneberry, Round-lobed hepatica.

More Utah flowers

Blue columbine (Aquilegia coerulea)

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★ CO state flowerNative

🌼 Blooms in UT: June–July
Red baneberry (Actaea rubra)

Red baneberry

Actaea rubra

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Plains pricklypear (Opuntia polyacantha)

Plains pricklypear

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🌼 Blooms in UT: April–June

Sources