Trifolium retusum
Teasel clover
(c) Oleksandr Shynder, some rights reserved (CC BY) · licence
Family: Fabaceae · Type: Herb · Not Native
Trifolium retusum (Teasel clover) is a non-native California herb in the Fabaceae family, recognized by . Key features: Cascade Range only, curved sepals > corolla.
Teasel clover is a naturalized annual herb found in the northern California Ranges in disturbed roadsides at elevations of 150 to 800 meters. Flowering from May to August, this plant produces white to pink flowers with delicate rounded or occasionally toothed banner petals. Growing with erect to ascending glabrous stems, it forms compact plants typically less than 30 centimeters tall. Its leaves are characterized by distinctive triangular stipules that abruptly narrow to an awl-shaped tip, with leaflets that are obovate and 0.7 to 1.9 centimeters long, featuring prominent veining. Flowers are reflexed when in fruit, with calyxes 4 to 5 millimeters long and upper calyx lobes curved and longer than the lower lobes.
Identification and appearance
Key characters: 31 sympatric species. Key features: Cascade Range only, curved sepals > corolla
Habitat and range
Habitat: Disturbed roadsides
Elevation: 150-800 m
Outside California: United States, native to southern Europe, Mediterranean, northern Africa
Bloom period
Trifolium retusum blooms May-Aug.
How to tell it apart
vs Medicago: Trifolium flowers persist around fruits; Medicago flowers fall off leaving exposed coiled fruits.; vs Oxalis: Trifolium has pea-shaped flowers; wood-sorrels (Oxalis) have 5-petaled star-shaped flowers and heart-notched leaflets.; vs Melilotus: Trifolium flowers persist enclosing fruits; Melilotus flowers fall off leaving exposed ridged pods.; vs Castilleja: Trifolium has pea flowers and 3 toothed leaflets; paintbrush (Castilleja) has tubular flowers in colorful bracts.; vs Acmispon: Trifolium leaflets have toothed edges; Acmispon leaflets have smooth untoothed margins.
Frequently asked questions
Is Trifolium retusum native to California?
No. Trifolium retusum is not native to California (recorded as not native).
When does Trifolium retusum bloom?
Trifolium retusum blooms May-Aug.
What plant family does Trifolium retusum belong to?
Trifolium retusum is in the Fabaceae family, genus Trifolium.
What habitat does Trifolium retusum grow in?
Trifolium retusum grows in Disturbed roadsides.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · 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.