Fabaceae, Leguminosae, or Papilionaceae, commonly known as legume, pea, or bean Family, in the Order of Fabales, is a Family, the third largest land plant Family in terms of number of Species, behind only the Orchidaceae and Asteraceae, of Dicotyledonous flowering plants, with about 751 genera and approximately 19,000 known Species, cosmopolitan distribution. Plants trees, shrubs, or herbs, sometimes climbing or decumbent, very often bearing root nodules producing nitrogen-fixing bacteria. Stems are erect, climbing, or twining. Leaves are compound, rarely simple, sometimes terminal leaflets reduced to tendril or thorny hairs, alternate, rarely opposite, pinnate or bipinnate, less often palmately compound or 3-foliolate, seldom 1-foliolate, or modified into narrow phyllodes. Petioles are present or absent. Stipules and stipels are present or absent, and sometimes stipules develop into spines. Flowers are bisexual, rarely unisexual, actinomorphic, or zygomorphic mostly in racemes, corymbs, spikes, heads or panicles. Bracts or bractlets are often present. Sepals are five, free or connate, usually unequal, and sometimes bilabiate. Petals are usually isomerous with sepals, seldom fewer or none, imbricate or valvate, distinct and often highly differentiated into papilionaceous corolla, upper petal (standard) outmost, with two lateral petals (wings) parallel with each other, with lower two innermost petals usually connate by their lower margins and forming a keel. Stamens are mostly ten, sometimes fewer or more, free or connate to diadelphous, sometimes totally connate to monadelphous. Anthers are uniform or dimorphic, 2-locular, often longitudinally dehiscent. Ovary is superior, 1-locular or sometimes transversely, and rarely longitudinally septate. Ovules are one to numerous, marginal placenta, and inserted on adaxial suture. Styles and stigmas are solitary. Legumes are dehiscent by one or both sutures or indehiscent, sometimes winged, sometimes jointed and breaking up into 1-seeded segments. Seeds are usually exalbuminous, sometimes strophiolate. Cotyledons are large, fleshy or foliaceous. Twenty-three Species, belonging to different genera, are illustrated in this chapter.