Trifolium vesiculosum var. vesiculosum

Upright annual herb; stems 15–40 cm long, simple or branched, glabrous, angled, often reddish. Leaves palmately trifoliolate, short- to long-petiolate; leaflets lanceolate, 15–40 mm long, 5–15 mm wide, glabrous, acutely serrate-dentate, usually apiculate, prominently veined below, often with a pale arrow-shaped spot above; stipules scarious, prominently nerved. Inflorescence many-flowered, appearing terminal, solitary, initially broadly conical, finally obloid to ovoid-cylindric, 3–6 cm long, 2.5–3.5 cm wide, subsessile to pedunculate; flowers sessile. Calyx 6–7 mm long, tube cylindric, 20–30-veined, throat open, teeth about as long as tube, almost equal, spiny, reflexed in fruit; corolla 12–15 mm long, pale pink to purple, persistent; standard lanceolate, claw broad, tapering; keel and wings much shorter than standard. Pod obloid, c. 4 mm long, scarious, included in calyx tube; seeds 2–3, more or less ovoid, c. 1.2 mm long, brown.  Flowers spring-early summer.