Ornithopus perpusillus

Scientific profile

Ornithopus perpusillus is a delicately built, softly hairy annual herb, typically growing to about 19 cm in height, with creeping to ascending stems. The leaves are imparipinnate, each bearing several pairs of small, oblong-elliptic leaflets, and at the leaf base there are two tiny linear stipules. The inflorescence is a long-stalked, tight cluster of 3–8 small pea-like flowers, each only 3–5 mm long and pale pink or whitish. Flowering takes place from May to July. The fruit is a narrow, compressed pod 1–2.5 cm long, deeply constricted between the seeds, with a short, sometimes hooked beak; the surface is net-veined and pubescent. As a member of the pea family (Fabaceae) it forms nitrogen-fixing root nodules, and arbuscular mycorrhiza has been recorded. The plant is a native of Great Britain, where it occupies open, sunny habitats on free-draining, distinctly acidic and impoverished substrates, such as sandy heaths, gravelly tracks and short, thin grassland. The diaspores are very light, weighing around 1 mg.