Trifolium pilulare

Erect annual herb; stems 10–50 cm long, branching, villous. Leaves pinnately trifoliolate, long- and short-petiolate; leaflets obovate to obcordate, 4–12 mm long, 3–7(–12) mm wide, appressed-hairy, apex notched, rounded or truncate, often apiculate, upper margins minutely denticulate; stipules membranous. Inflorescence with 1 or 2 fertile flowers and numerous sterile flowers developing later, axillary, ovoid or globular, 6–9 mm long, 6–9 mm wide, pedunculate; flowers sessile. Fertile calyx c. 6 mm long, densely villous, tube cylindric, teeth as long or longer than tube, equal, acute, plumose; sterile calyx with solid, stalk-like tube, teeth linear, plumose; corolla 6–7 mm long, white; standard slightly longer than wings and keel. Fruiting heads separating as a whole from stem; pod ovoid-obtuse, membranous, included in calyx tube; seeds 1 or 2, ovoid-globular,c. 2 mm long, dark brown, shiny. Flowers Oct. (1 record).