Chilean Bird's Foot Trefoil

Annual, Herbs, Taproot present, Nodules present, Stems prostrate, trailing, or mat forming, Stems less than 1 m tall, Stems solid, Stems or young twigs sparsely to densely hairy, Leaves alternate, Leaves petiolate, Stipules inconspicuous, absent, or caducous, Stipules persistent, Stipules free, Stipules reduced to glands, Leaves compound, Leaves pinnately 3-foliolate, Leaves odd pinnate, Leaf or leaflet margins entire, Leaflets opposite, Leaflets alternate or subopposite, Leaflets 3, Leaflets 4, Leaflets 5-9, Leaves glabrous or nearly so, Flowers solitary in axils, or appearing solitary, Inflorescence sessile or subsessile, Inflorescence axillary, Bracts conspicuously present, Flowers zygomorphic, Calyx 5-lobed, Calyx hairy, Petals separate, Corolla papilionaceous, Petals clawed, Petals red, Petals orange or yellow, Petals bicolored or with red, purple or yellow streaks or spots, Banner petal ovoid or obovate, Wing petals narrow, oblanceolate to oblong, Wing tips obtuse or rounded, Keel tips obtuse or rounded, not beaked, Stamens 9-10, Stamens or anthers dimorphic, alternating large and small, Stamens diadelphous, 9 united, 1 free, Filaments glabrous, Style terete, Style persistent in fruit, Fruit a legume, Fruit unilocular, Fruit freely dehiscent, Fruit elongate, straight, Fruit or valves persistent on stem, Fruit coriaceous or becoming woody, Fruit exserted from calyx, Fruit internally septate between the seeds, Valves twisting or coiling after dehiscence, Fruit glabrous or glabrate, Fruit hairy, Fruit 2-seeded, Fruit 3-10 seeded, Seeds reniform, Seed surface smooth, Seeds olive, brown, or black.

Acmispon wrangelianus is a species of legume native to California and Oregon in the southwestern United States. It is known by the common names Chilean bird's-foot trefoil and Chile lotus. Despite its common name, it is not from Chile. It can be found in many types of habitat, including disturbed areas. This is a hairy, prostrate annual herb. Its slender branches are lined with leaves each made of generally four small leaflets. The inflorescence is composed of a solitary yellow pealike flower around a centimeter wide. The fruit is a legume pod one to two centimeters (0.39 to 0.79 in) long.