Caulanthus cooperi
Cooper caulanthus
(c) Matt Berger, some rights reserved (CC BY) · licence
Family: Brassicaceae · Type: Herb · Native
Caulanthus cooperi (Cooper caulanthus) is a native California herb in the Brassicaceae family, recognized by weak wavy stems and curved reflexed fruits.
Cooper caulanthus is a California native annual found in northern Transverse Ranges, eastern Peninsular Ranges, southern Sierra Nevada Eastern Boundary, and Desert regions in open, sandy, gravelly soil among shrubs at elevations of 300 to 2,500 meters. Flowering from March to April, this plant produces purple or yellow-green flowers 4.5 to 9 millimeters long with delicate petals. Growing with weak, wavy stems 10 to 80 centimeters tall that branch distally and are generally glabrous, it develops distinctive foliage. Its basal leaves are oblanceolate to spoon-shaped, coarsely dentate to lobed, while cauline leaves are sessile, lanceolate to oblong, with bases that are lobed or clasping. The fruit is a slender, generally curved cylindric structure 2 to 6 centimeters long, bearing 24 to 48 small oblong seeds.
Identification and appearance
Key characters: 12 sympatric species; weak wavy stems and curved reflexed fruits are diagnostic
Habitat and range
Habitat: Common. Open, sandy, gravelly soil, generally among shrubs
Elevation: 300-2500 m
California counties: San Bernardino, Inyo, Kern, Lake, Los Angeles, Mono, Riverside, San Diego, Imperial
Outside California: to southwestern Utah, western Arizona, Baja California
Bloom period
Caulanthus cooperi blooms Mar-Apr.
How to tell it apart
vs Streptanthus: Seed pods are cylindrical and round versus flattened blade-like pods in Streptanthus.; vs Sisymbrium: Petals are distinctively crinkled and papery versus smooth petals in Sisymbrium.; vs Hirschfeldia: Young pods reflex sharply downward versus pointing upward or outward.; vs Boechera: Pods reflex downward and contain wingless seeds versus erect pods with winged seeds.; vs Brassica: Young seed pods bend sharply downward versus pointing upward in Brassica.
Frequently asked questions
Is Caulanthus cooperi native to California?
Yes. Caulanthus cooperi is native to California (recorded as native).
When does Caulanthus cooperi bloom?
Caulanthus cooperi blooms Mar-Apr.
Where in California does Caulanthus cooperi grow?
Caulanthus cooperi occurs in San Bernardino, Inyo, Kern, Lake, Los Angeles, Mono, Riverside, San Diego and other counties, at elevations of 300-2500 m.
What plant family does Caulanthus cooperi belong to?
Caulanthus cooperi is in the Brassicaceae family, genus Caulanthus.
What habitat does Caulanthus cooperi grow in?
Caulanthus cooperi grows in Common. Open, sandy, gravelly soil, generally among shrubs.
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.