The species are mostly herbaceous perennial plants 0.3-1.5 m tall, but some are annual plants and a few are shrubs up to 3 m tall, with one, Lupinus jaimehintoniana, a tree 8 m high with a trunk 20 cm in diameter, from the Mexican state of Oaxaca. They have a characteristic and easily recognised leaf shape, with soft green to grey-green or silvery leaves with the blades usually palmately divided into 5–17 leaflets or reduced to a single leaflet in a few species of the southeastern United States; in many species, the leaves are hairy with silvery hairs, often densely so. The flowers are produced in dense or open whorls on an erect spike, each flower 1-2 cm long, with a typical peaflower shape with an upper 'standard', two lateral 'wings' and two lower petals fused as a 'keel'. The fruit is a pod containing several seeds.