Annual. Stems prostrate to erect, 5–30 cm. Herbage glabrous. Leaflets obovate, 5–15 mm long, serrate; stipules ovate, lacerate. Racemes axillary, umbellate, 1–2 cm wide, longer than the leaves, subtended by a glabrous, saucer-shaped involucre with spine-tipped lobes. Flowers purple, 6–10 mm long; calyx glabrous; sepals narrowly deltoid, spine-tipped, 3–5 mm long, shorter than the corolla. Legume often rupturing the calyx, 2–3 mm long with 1 or 2 seeds (
Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
Trifolium variegatum is distinguished from T. microcephalum by the former’s glabrous involucre and herbage. T. microcephalum has a villous involucre and villous to hirsute herbage (
Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).