Black Vetch

Perennial, Herbs, Vines, twining, climbing, Taproot present, Nodules present, Stems prostrate, trailing, or mat forming, Stems less than 1 m tall, Stems 1-2 m tall, Climbing by tendrils, Stems solid, Stems or young twigs glabrous or sparsely glabrate, Stems or young twigs sparsely to densely hairy, Leaves alternate, Leaves petiolate, Stipules conspicuous, Stipules green, triangulate to lanceolate or foliaceous, Stipules persistent, Stipules free, Stipules toothed or laciniate, Leaves compound, Leaves even pinnate, Leaf or leaflet margins entire, Leaflets opposite, Leaflets alternate or subopposite, Leaflets 10-many, Leaves glabrous or nearly so, Inflorescences racemes, Inflorescence axillary, Inflorescence secund, flowers mostly on one side, Bracts very small, absent or caducous, Flowers zygomorphic, Calyx 5-lobed, Calyx glabrous, Petals separate, Corolla papilionaceous, Petals clawed, Petals ochroleucous, cream colored, Petals blue, lavander to purple, or violet, Banner petal ovoid or obovate, Wing petals narrow, oblanceolate to oblong, Wing petals auriculate, Wing tips obtuse or rounded, Keel tips obtuse or rounded, not beaked, Stamens 9-10, Stamens diadelphous, 9 united, 1 free, Filaments glabrous, Style terete, Style sharply bent, Style hairy, Style hairy on one side only, Style with distal tuft of hairs, Fruit a legume, Fruit stipitate, Fruit unilocular, Fruit freely dehiscent, Fruit oblong or ellipsoidal, Fruit exserted from calyx, Valves twisting or coiling after dehiscence, Fruit glabrous or glabrate, Fruit 3-10 seeded, Seeds ovoid to rounded in outline, Seed surface smooth, Seeds olive, brown, or black, Seed surface mottled or patchy.

Vicia nigricans is a species of vetch known by the common name black vetch. It has a disjunct distribution, its two subspecies divided by thousands of miles in range. The northern subspecies, ssp. gigantea (giant vetch), is native to western North America from Alaska to northern California, where it occurs in coastal and moist inland habitat and disturbed areas. The southern subspecies, ssp. nigricans, occurs in southern South America, in Argentina and Chile.

This vetch is a perennial herb with stout, hollow, and ridged climbing stems that may reach two meters in length. It attaches to objects and other plants by its large branched tendrils for support. The leaves are made up of 9 to 13 pairs of lance-shaped or elongated oval leaflets that may measure up to 4 centimeters in length. The inflorescence is a one-sided raceme of up to 15 or 20 flowers which have pale pink to dark reddish purple or sometimes yellowish to orange corollas. The flowers, each with a calyx about half as long as the corolla, are 1 to 2 centimeters long. They yield fruits which are legume pods measuring up to 4 centimeters long by 1.5 wide. As they dry they turn black.