Herbs perennial, 3–22 cm, glabrous or hairy, often mat-forming. Stems decumbent to ascending, much-branched. Leaves palmate; stipules ovate to lanceolate, 0.3–1.2 cm, mar­gins entire, serrate, or slightly lacerate, apex acute to acumi­nate; petiole 1–4.5 cm; petiolules 0.1–0.5 mm; leaflets 3, blades obovate, oblanceolate, or elliptic, 0.3–2 × 0.2–0.5 cm, base cuneate, veins promi­nent, margins ± dentate, serrate, or setose, apex acute, rounded, or retuse, surfaces glabrous or slightly villous. Peduncles 0.5–2 cm. Inflorescences axillary or terminal, 1–9-flowered, solitary or subglobose, 1–1.6 × 0.3–1.2 cm; involucres campanulate, 2–5 mm, incised nearly to base, lobes 2–8, lanceolate. Pedicels erect, 1 mm; bracteoles absent. Flowers 10–16 mm; calyx tub­ular, 2–10 mm, glabrous or pubescent, veins 10, tube 4–7 mm, lobes equal, triangular-subulate, orifice open; corolla white, pink, or lavender, keel petals usually purple-spotted, 8–16 mm, banner oblong, 8–13 × 2–5 mm, apex emarginate. Legumes oblong, 2–4 mm. Seeds 1 or 2, brown, mottled, mitten-shaped, 1–2 mm, dull. 2n = 16.

Distribution

w United States, nw Mexico.

Discussion

Subspecies 4 (4 in the flora).

Morphological intergradation among subspecies of Trifolium monanthum may be indicative of low genetic barriers to crossing. It might be just as plausible to divide T. mononathum into two species instead of four subspecies (J. M. Gillett 1980), with T. monanthum encompassing populations with white rhizomes, and T. multicaule encompassing populations with taproots.

Trifolium monanthum often forms dense mats.

Selected References

None.

Lower Taxa

Trifolium monanthum subsp. grantianum, Trifolium monanthum subsp. monanthum, Trifolium monanthum subsp. parvum, Trifolium monanthum subsp. tenerum

Key

1	Herbs glabrous or sparsely hairy, mat-forming; stems from thin to thick woody roots, rhizomes slender, white; peduncles straight or bent upwards at steep angle distally; flowers 1–5.	> 2
2	Inflorescences (1 or)2–4-flowered; peduncles straight; leaflet blades obovate to oblanceo­late, margins ± dentate, apex rounded or retuse.	Trifolium monanthum subsp. monanthum
2	Inflorescences 1–5-flowered; peduncles bent upwards at steep angle distally; leaflet blades oblanceolate or elliptic, margins setose, apex acute.	Trifolium monanthum subsp. grantianum
1	Herbs densely hairy, decumbent to ascending; stems from thickened woody taproots, rhizomes absent; peduncles bent upwards at steep angle distally; flowers 1–9.	> 3
3	Leaflet blade apex rounded, margins dentate.	Trifolium monanthum subsp. parvum
3	Leaflet blade apex acute, margins serrate or setose.	Trifolium monanthum subsp. tenerum