Herbs annual, 8–30 cm, canes­cent. Stems erect, branched from base and distally, or unbranched. Leaves palmate; stip­ules ovate, 0.4–1.2 cm, margins entire, ciliate, apex often purple, acuminate, setaceous; petiole 0.5–8 cm; petiolules 0.5–1 mm; leaflets 3, blades obovate or elliptic, 0.5–3 × 0.3–1.2 cm, base cuneate, veins obscure or slightly thickened, margins dentate, apex rounded or emarginate, surfaces pilose. Peduncles 3–11 cm. Inflorescences terminal or axillary, 25–50-flowered, ovoid-ellipsoid, 1–2.5 × 1.2–2.5 cm; involucres absent. Pedicels absent; bracteoles cuplike, to 0.5 mm. Flowers 6–10 mm; calyx tubular, 8–14 mm, densely pubescent, veins 20–30, tube 1–2 mm, lobes nearly equal, appearing rigidly erect, linear-setaceous, plumose, sinuses acute, orifice open; corolla sometimes absent, red-violet, often with white tips, 4–6 mm, banner ovate-oblong, 7–8 × 2–3 mm, apex broadly rounded, apiculate. Legumes obovoid, 3–3.5 mm. Seeds 1, yellow-brown, ellipsoid, 2–2.5 mm, smooth.

Phenology: Flowering Apr–May.
Habitat: Grassy slopes, meadows, heavy adobe/clay soils, oak woodland foothills.
Elevation: 0–1400 m.

Distribution

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Calif.

Discussion

D. Isely (1998) stated that Central Valley populations of Trifolium columbinum appeared to be extinct and populations outside that region (and here recognized as the same taxon) were similar in calyx and corolla proportions. It is rather widespread in California, ranging from Humboldt County southward to Santa Barbara County, and eastward into counties ranging from Shasta southward to Inyo, Kern, and Placer counties.

Trifolium albopurpureum var. olivaceum (Greene) Isely and T. columbinum var. olivaceum (Greene) Jepson are illegitimate names that pertain here (D. J. Keil 2019).

Selected References

None.

Lower Taxa

None.