Plants annual, biennial, or perennial herbs, with taproots or rhizomes. Stems erect to more commonly spreading or climbing, sometimes mat-forming, angled or ridged but not winged, unbranched or more commonly branched, unarmed, glabrous or pubescent with nonglandular hairs. Leaves alternate, even-pinnately compound with 2 to numerous leaflets, the petiole short or absent, unwinged, the rachis extended into a conspicuous, unbranched or branched tendril (this absent or poorly developed and bristlelike elsewhere). Stipules more or less leaflike, in some species with a basal outgrowth or lobe of tissue on 1 side, this rounded or more commonly triangular, descending or clasping the stem, the margins otherwise entire or toothed, the venation mostly inconspicuous, persistent; stipels absent. Leaflets variously shaped (sometimes even on the same plant), the margins entire, the surfaces glabrous or hairy, pinnately veined or only the midvein visible. Inflorescences axillary, spikelike racemes or clusters, sometimes reduced to solitary flowers, the bracts 1–3 mm long, shed early, bractlets absent. Calyces 5-lobed, the tube cylindric to bell-shaped, often at least slightly oblique, sometimes somewhat pouched on 1 side at the base, more or less 2-lipped, the lobes subequal or the 3 lower lobes longer than the upper 2, variously shaped, sharply pointed at their tips, glabrous or hairy. Corollas papilionaceous, blue, purple, red, yellow, or white, sometimes with darker nerves or appearing bicolorous), lacking conspicuous, contrasting markings near the base of the banner, the banner with a short, broad, stalklike base overlapping the wings, the expanded portion obovate to nearly circular, slightly to deeply notched at the tip, curved or bent upward or backward, the wings oblong to obovate, shorter than to slightly longer than the banner, usually curved over or around and fused to the keel below the midpoint, the keel shorter than the wings, boat-shaped, slightly to strongly curved upward, rounded or tapered to a bluntly or sharply pointed tip. Stamens 10, 9 of the filaments fused and 1 free nearly to the base, all similar in length, the free portions of the filaments slender, not broadened toward their tips the anthers small, attached at the base, all similar in size, yellow or occasionally orange. Ovary sessile or short-stalked, glabrous, the style abruptly curved or bent upward toward the base, not flattened, usually hairy toward the tip, the hairs encircling the style or in a tuft on the outer side, more or less persistent at fruiting, the stigma terminal, short. Fruits legumes, mostly oblong to elliptic, tapered asymmetrically to a sharply pointed or more commonly beaked tip (rounded elsewhere), flattened, slightly constricted between the seeds or not, straight or slightly curved upward, 2- to numerous-seeded, dehiscing by 2 valves, these green to brown at maturity, usually twisting spirally after dehiscence. Seeds oblong to oblong-elliptic, broadly ovate, or circular in outline, flattened or not, the surface smooth, reddish brown to dark brown, sometimes mottled, often dull. About 160 species, North America to South America, Europe, Asia, Africa, Pacific Islands, most diverse in temperate regions.

Vicia is a member of the tribe Fabeae, which is one of the most economically important groups in the family and also includes the related genera Lathyrus L. (sweet pea, vetchling), Lens Mill. (lentil), and Pisum L. (garden pea). Vicia is very similar to Lathyrus, but differs in having unwinged stems, generally smaller leaflets and flowers, filament tubes ending obliquely, and unflattened styles with hairs usually encircling the tip. Preliminary findings from molecular phylogenetic studies by Wojciechowski et al. (2004) suggest that, as currently circumscribed, the genus Vicia may not be natural, comprising two or more groups, some of which may be more closely related to other genera in the tribe than to the rest of Vicia. Determinations of taxa within Vicia can be a bit confusing, requiring multiple characters to separate species (Gunn, 1968, 1979; Isely, 1998). Leaf characters are generally relatively similar, with only minor variation in leaflet number, size, pubescence, and tendril branching. Self-pollinating species are particularly variable in plant size, number of leaflets, pubescence, flower color, and seed size and color. Seed characters are sometimes useful, but are overlapping (Lassetter, 1978). Some Old World species that were introduced long ago for cover crops have been collected a few times as escapes in Missouri, and might still persist in waste areas.

Vicia is widely cultivated as a cover crop and green manure for soil improvement and erosion control. The leaves of all species are palatable and nourishing to livestock, with few toxicity problems. However, the seeds of V. sativa and V. villosa are associated with neurotoxicity and skin problems when eaten by livestock (Burrows and Tyrl, 2001). Seeds of V. faba L. (fava bean, broad bean) are commonly eaten by people in Europe, the Mediterranean region, and China; however, unless cooked thoroughly they cause a kind of haemolytic anemia known as favism, particularly among a genetically predisposed segment of the population (Sokolov, 1984).