Acmispon americanus var. americanus
American bird's foot trefoil
Photo by Chez Brungraber
Family: Fabaceae · Type: Herb · Native
Acmispon americanus var. americanus (American bird's foot trefoil) is a native California herb in the Fabaceae family, recognized by annual habit and dehiscent fruits.
American bird's foot trefoil is a California native annual found in coast, chaparral, mountain forest, and disturbed areas throughout California (except Desert Southwest) at elevations below 2,400 meters. Flowering from May to October, this plant produces white to yellow or pink flowers 5 to 9 millimeters long, with wings nearly equal to the keel. Growing prostrate to erect with hairy stems 0.5 to 6 decimeters tall, it can be simple or openly branched. Its leaves are pinnate with three leaflets generally 10 to 20 millimeters long, lanceolate to elliptic in shape. The fruit is a dehiscent pod 1.5 to 3 centimeters long with a curved beak, containing 3 to 8 seeds.
Identification and appearance
Key characters: 45 sympatric species; distinguished by annual habit and dehiscent fruits
Habitat and range
Habitat: Coast, chaparral, mountain forest, water courses, roadsides, other disturbed areas
Elevation: < 2400 m
California counties: Butte, Modoc, San Diego, San Bernardino, Kern, Alpine, Orange, Tulare, Alameda, Riverside, Mono, Shasta, Placer, San Luis Obispo, Marin, El Dorado, Nevada, Los Angeles, Lassen, Madera, Plumas, Trinity, Lake, Siskiyou, Sierra, Fresno, Merced, Tehama, Colusa, Mendocino, Yuba, Contra Costa, Del Norte, Napa, Tuolumne, Sonoma, San Mateo, Ventura, Monterey, Santa Barbara, Stanislaus, Santa Cruz, Mariposa, Sacramento, Calaveras, Glenn, Amador, Santa Clara, Solano, Yolo, Humboldt, San Joaquin, Inyo
Outside California: to Canada, central United States, Mexico
Bloom period
Acmispon americanus var. americanus blooms May-Oct.
How to tell it apart
vs Lotus: Same genus - Lotus is an older name for Acmispon, now considered synonymous.; vs Ottleya: Acmispon has yellow pea-shaped flowers in umbels; Ottleya (a buckwheat relative) has tiny white/pink flowers without pea shape.; vs Eriogonum: Acmispon has compound leaves with 3 leaflets; buckwheats (Eriogonum) have simple leaves.; vs Genista: Acmispon leaves are compound with 3 leaflets; Genista (broom) has simple or very small trifoliate leaves on ridged green stems.; vs Hosackia: Acmispon has tiny gland-like stipules; Hosackia has conspicuous papery or leaf-like stipules at leaf bases.
Frequently asked questions
Is Acmispon americanus var. americanus native to California?
Yes. Acmispon americanus var. americanus is native to California (recorded as native).
When does Acmispon americanus var. americanus bloom?
Acmispon americanus var. americanus blooms May-Oct.
Where in California does Acmispon americanus var. americanus grow?
Acmispon americanus var. americanus occurs in Butte, Modoc, San Diego, San Bernardino, Kern, Alpine, Orange, Tulare and other counties, at elevations of < 2400 m.
What plant family does Acmispon americanus var. americanus belong to?
Acmispon americanus var. americanus is in the Fabaceae family, genus Acmispon.
What habitat does Acmispon americanus var. americanus grow in?
Acmispon americanus var. americanus grows in Coast, chaparral, mountain forest, water courses, roadsides, other disturbed areas.
Related species
Other California species in the same genus, family, or bioregion.
- Acmispon argophyllus — Silver birds foot trefoil
- Acmispon argophyllus var. adsurgens — San clemente island bird's-foot trefoil
- Acmispon argophyllus var. argenteus — Channel Islands silver lotus
- Acmispon argophyllus var. argophyllus — Southern California silver lotus
- Acmispon argophyllus var. fremontii — Fremont's silver lotus
- Acmispon argophyllus var. niveus — Santa cruz island bird's-foot trefoil
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.