Fabaceae (Leguminosae)

The Fabaceae are herbs, vines, shrubs, trees, and lianas found in both temperate and tropical areas. They comprise one of the largest families of flowering plants, numbering 630 genera and 18,000 species. The leaves are stipulate, nearly always alternate, and range from bipinnately or palmately compound to simple. The petiole base is commonly enlarged into a pulvinus that commonly functions in orientation of the leaves (sometimes very responsively, as in the sensitive plant, Mimosa pudica).  The flowers are usually bisexual, actinomorphic to zygomorphic, slightly to strongly perigynous, and commonly in racemes, spikes, or heads. The perianth commonly consists of a calyx and corolla of 5 segments each.  The androecium consists of commonly 1- many stamens (most commonly 10), distinct or variously united, sometimes some of them reduced to staminodes.  The pistil is simple, often stipitate, comprising a single style and stigma, and a superior ovary with one locule containing 2-many marginal ovules. The fruit is usually a legume, sometimes a samara, loment, follicle, indehiscent pod, achene, drupe, or berry.  The seeds often have a hard coat with hourglass-shaped cells, and sometimes bear a u-shaped line called a pleurogram.

Three subfamilies (Mimosoideae, Caesalpinioideae, and Faboideae) are recognized as further characterized below.

Each "thumbnail" image below is linked to an expanded treatment of the corresponding subfamily.

Mimosoideae Mostly trees or shrubs.  Leaves mostly bipinnate.  Corolla usually not showy, actinomorphic, sympetalous, the lobes valvate.  Stamens 10-numerous, often monadelphous, showy.  Pollen released in monads, tetrads, or polyads.  Seeds with u-shaped line (pleurogram) present.
Caesalpinioideae.  Mostly trees or shrubs.  Leaves mostly pinnate, sometimes bipinnate, rarely apparently simple.  Corolla usually showy,  zygomorphic, the petals imbricate, posterior (upper or banner) petal innermost in bud.  Stamens 10 or fewer, distinct, usually not showy, some commonly reduced to staminodes.  Pollen released in monads.  Seeds with u-shaped line (pleurogram) usually lacking.
Faboideae.  Mostly herbs, shrubs, or trees.  Leaves pinnate or palmate to trifoliolate or apparently simple.  Corolla usually, showy, zygomorphic, the petals imbricate, posterior (upper or banner) petal outermost in bud.  Stamens 10 or 9 + 1 (diadelphous), not showy.  Pollen released in monads.  Seeds with u-shaped line (pleurogram) lacking.

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