Ranunculus bonariensis var. trisepalus
Carter's buttercup
(c) Steve Matson, some rights reserved (CC BY) · licence
Family: Ranunculaceae · Type: Herb · Native
Ranunculus bonariensis var. trisepalus (Carter's buttercup) is a native California herb in the Ranunculaceae family, recognized by 3 sepals diagnostic among buttercups.
Carter's buttercup is a California native annual found in northern Sierra Nevada foothills and the Central Valley in vernal pools and stream edges at elevations of 30 to 1,000 meters. Flowering from March to May, this plant produces small yellow flowers about 1.5 to 2.5 millimeters wide. Growing 4 to 20 centimeters tall with decumbent stems that root at the lowest nodes, it can spread horizontally or grow upright. Its simple cauline leaves are elliptic to ovate, 0.8 to 2.3 centimeters long with entire or finely toothed margins and widely rounded tips. The fruit is a small lenticular body with a thick, smooth wall and a short beak.
Identification and appearance
Key characters: 22 sympatric species; 3 sepals diagnostic among buttercups
Habitat and range
Habitat: Vernal pools, stream edges
Elevation: 30-1000 m
California counties: Butte, Calaveras, El Dorado, Yuba, Stanislaus, Placer, Tehama, Sacramento, Amador, San Joaquin, Merced, Sutter
Outside California: South America
Bloom period
Ranunculus bonariensis var. trisepalus blooms Mar-May.
How to tell it apart
vs Lasthenia: Ranunculus has separate petals around a central disk; Lasthenia has many tiny ray flowers around a disk (composite head).; vs Bowlesia: Ranunculus has glossy yellow petals in conspicuous flowers; Bowlesia has tiny white flowers in umbels with divided leaves.; vs Potentilla: Ranunculus has nectaries at petal bases and many pistils; Potentilla has no nectaries and styles attached to ovary sides.; vs Papaver: Ranunculus has 5 petals and many pistils; Papaver has 4 crinkled petals and a single large stigma disk.; vs Oxalis: Ranunculus has glossy separate petals; Oxalis has clover-like leaves and tubular flowers that close at night.
Frequently asked questions
Is Ranunculus bonariensis var. trisepalus native to California?
Yes. Ranunculus bonariensis var. trisepalus is native to California (recorded as native).
When does Ranunculus bonariensis var. trisepalus bloom?
Ranunculus bonariensis var. trisepalus blooms Mar-May.
Where in California does Ranunculus bonariensis var. trisepalus grow?
Ranunculus bonariensis var. trisepalus occurs in Butte, Calaveras, El Dorado, Yuba, Stanislaus, Placer, Tehama, Sacramento and other counties, at elevations of 30-1000 m.
What plant family does Ranunculus bonariensis var. trisepalus belong to?
Ranunculus bonariensis var. trisepalus is in the Ranunculaceae family, genus Ranunculus.
What habitat does Ranunculus bonariensis var. trisepalus grow in?
Ranunculus bonariensis var. trisepalus grows in Vernal pools, stream edges.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.