|Abstract||Usually lianas, sometimes shrubs or small trees, provided with characteristic unicellular hairs which are generally centrally attached (fig. 11). Leaves opposite, rarely subopposite or in whorls of 3, mostly petioled, simple and mostly entire, often provided with superficial glands beneath, especially at the base. Stipules mostly present, variable. Inflorescences simple or slightly paniculate at the base, bracteate, raceme-like; pedicels articulated, bracteolate. Flowers often conspicuous, bisexual, but often parts of the gynoecium or androecium abortive, or rarely polygamous, actinomorphic to zygomorphic. Sepals 5, free or slightly connate, persistent, calyx outside sometimes provided with 1-10 distinct glands. Petals 5, free, imbricate, mostly cochlear, nearly always clawed, margin often ciliate, dentate or fimbriate. Disk inconspicuous, sometimes accrescent. Stamens (in Mal.) 10, sometimes unequal; filaments often connate at the base; anthers basifix or dorsifix, introrse, sometimes with enlarged connective, 2-celled, dehiscing lengthwise. Ovary superior, with generally 3 (in extra-Mal. spp. rarely 2, 4 or 5) carpels, cells, and lobes. Styles as much as carpels, persistent, free, with a terminal, sometimes little developed stigma. Ovules 1 per cell, hemi-anatropous, hanging from an almost axillary placenta. Fruit a schizocarp of which the mericarps may dehisce dorsally, mericarps mostly winged in various ways (samara), seldom fleshy and forming a drupe (in extra-Mal. spp. a capsule or berry may occur). Seed with a large and mostly straight, rarely curved, embryo; endosperm none.|
Distr. About 57 genera and 700 spp., almost entirely confined to the tropics. The bulk of the family occurs in the New World; in a general way, the distributional frontiers of the larger taxa often coincide with important geographical demarcations.