|Abstract||Evergreen trees. Twigs terete to quadrangular, the younger ones mostly with four narrow ribs or wings, with thickened nodes, petiole-bases mostly connected by a faint line. Leaves with minute or rudimentary stipules, opposite, simple, entire, penninerved, shortly petioled, with arched or almost straight nerves mostly anastomosing in a marginal vein. Inflorescence terminal or axillary, sometimes below the leaves, paniculate, copiously branched to extremely depauperate, branched up to the third order, with decussate side axes which are sometimes arranged (sub)- verticillately or subumbellately by contraction, either ending in profuse to very poor racemules, or in cymoid florescences. Bracts mostly small to minute, sometimes with rudimentary stipules. Flowers (very) small, shortly pedicelled, bisexual, sometimes by reduction unisexual and then trees dioecious, actinomorphous, perito epigynous, (4—)5(—6)-isomerous, sometimes with twice the number of stamens; receptacle widely campanulate. Sepals valvate, triangular to deltoid, mostly persistent. Petals more or less rudimentary, sometimes absent, alternisepalous, inserted on the margin of the receptacle, inflexed and enveloping the stamens, valvate, rarely imbricate, sometimes cohering, soon caducous. Stamens if isomerous epipetalous, (alternisepalous), inserted on the margin of the receptacle, inflexed in bud, persistent or caducous; filaments sometimes very short; connective wide, with or without a tendency to conduplication, or completely conduplicate, sometimes with a dorsal tubercle or a large outgrowth; anthers adnate, marginal or submarginal, linear to semiorbicular, lengthwise dehiscent, introrse to latrorse. Ovary superior or inferior, 2—4(—5)-carpellate, 1—6-locular, septs not, or rarely partly, connate; style terminal, rather long to short, ± terete, mostly persistent; stigma capitate or punctate. Ovules situated in horizontal or vertical position, 1, 2, 3, or many per locule, anatropous; placentation parietal, septal, or basal. Fruit superior or ½- or ¾-inferior, a chartaceous or woody capsule, subglobose to ellipsoid, small to big, loculicidally dehiscent with 2-6 valves, on the top often with the persistent style and stigma. Seeds few or many, flat, usually small, depressed-ellipsoid, situated basally, apically, centrally, or laterally in its membranous wing in which the raphe is running freely; endosperm none; embryo straight.|
Distribution. Pantropical, 5 genera and 11 spp., 3 genera in Indo-Malesia (of which one endemic in Borneo), one monotypic genus in S. Africa (Rhynchocalyx) and one in Peru and Bolivia (Alzatea).