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The Fabaceae is the third largest family of angiosperms, and is second only to the Poaceae in economic importance. The family is nearly cosmopolitan (occurring worldwide) in a wide range of habitats, but are somewhat better represented in dry regions (east of the Cascades) than moist regions (west of the Cascades). Economically important genera of food plants include most of our important plant protein sources: Arachis (peanuts), Cicer (chickpeas), Glycine (soybeans), Lens (lentils), Phaseolus (beans), Pisum (peas). Important forage plants include Medicago (alfalfa), Melilotus (sweet clover), Trifolium (clover), and Vicia (vetch). Ornamentally important genera include Acacia, Albizia (mimosa), Cercis (redbud), Gleditsia (honeylocust), Laburnum (goldenrain tree), Lathrys (sweet pea), Lupinus (lupine), Mimosa (sensitive plant), Robinia (locust), and Wysteria. Indigofera (indigo) is used as a source of blue dye.

The Fabaceae are herbs, shrubs, trees, or vines/lianas, climbing by twining or tendrils. They have a high nitrogen metabolism and unusual amino acids, and their roots are usually associated with nitrogen-fixing bacteria (Rhizobium). Their leaves are alternate, pinnately (or twice pinnately) compound, palmately compound, trifoliate, or unifoliolate, and entire to occasionally serrate. The terminal leaflets are sometimes modified into tendrils. Stipules are present, sometimes leaflike, or occasionally forming spines. The flowers of our genera are very unusual and easily recognized "pea" flowers. They are bilaterally symmetrical with a short, usually cup-shaped hypanthium, and have 5 fused sepals, 5 distinct or fused petals, the uppermost of which is usually differentiated in size, shape or color (i.e., forming a banner or standard). The 2 lower petals are usually fused to form a keel. There are usually 10 stamens which are all fused or which have 9 fused and one free. A single carpel forms the superior ovary, which matures into a legume ("pea pod") fruit.