57. Arachis Linnaeus, Sp. Pl. 2: 741. 1753.
落花生属 luo hua sheng shu
Herbs, annual. Stipules large, partly adnate with petiole, not spurred. Leaves paripinnate; leaflets opposite, subsessile. Inflorescences axillary, usually reduced to a solitary flower or a cluster of flowers. Hypanthium long. Calyx membranous; tube slender, elongating with flower development, 5-lobed, adaxial 4 lobes connate. Corolla yellow; standard almost orbicular, without an auricle; wings oblong, auriculate; keel apex slightly beaked. Stamens monadelphous, 10 but usually one absent; anthers dimorphic, long and short ones alternate, long ones almost dorsifixed, short ones basifixed. Ovary subsessile, base elongated and curved after fertilization, with 2 or 3(-6) ovules; style filiform; stigma terminal. Legume oblong, subtorulose, with thick walls, reticulated, 1-5(or 6)-seeded, not breaking into segments, indehiscent, apex not beaked.
About 22 species: tropics of America; one species (introduced) in China.
Two other species, Arachis glabrata Bentham and A. pintoi Krapovickas & W. C. Gregory, have been experimentally introduced for fodder in S China.