Slender serradella

Ornithopus pinnatus is a slender, prostrate to ascending annual herb in the Fabaceae, typically 10-40 cm long, with thin, flexuous, often glabrous or sparsely hairy stems arising from a slender taproot. The pinnate leaves bear 7-15 small, oblong to oblanceolate leaflets 3-8 mm long, glabrescent above and beneath, without stipule-like bracteoles beneath the inflorescence (a key distinction from the closely related O. perpusillus). Flowers are small, 5-7 mm long, with a bright yellow standard often veined or flushed orange-red, borne in axillary umbel-like clusters of one to five on long, slender peduncles. The calyx is tubular with short, narrowly triangular teeth. The fruit is a slender, curved, segmented loment 15-35 mm long, transversely constricted between the 4-8 one-seeded articles and breaking into segments at maturity. Seeds are small, kidney-shaped, smooth and brownish. The species occurs in open sandy heaths, dune slacks, coastal grasslands and disturbed siliceous ground across western Europe, the Mediterranean and Macaronesia, and is naturalised more widely.