Dioecious or sometimes polygamous, large trees with pithy thick bark and distinct leaf-scars. Leaves alternate, large, imparipinnate or paripinnate; leaflets opposite or ± opposite, oblique, entire or toothed, with glands on the underside of the teeth; stipules absent. Inflorescence an axillary panicle. Flowers unisexual, 5 (-6)-merous, actinomorphic. Disc 10-lobed or entire, annular, cupular or elongated. Calyx 5 (-6)-lobed, lobes equal, imbricate. Petals as many as sepals, oblong to narrowly oblong, concave, imbricate or valvate in bud. Stamens 10 in male flowers, 5-6 in bisexual flowers (but with sterile anthers) or vestigial or absent; anthers oblong. Ovary superior, of 2-5 free carpels, flat, 5-locular, placentation axile, ovules solitary in each locule, anatropous; styles as many as carpels, free or connate; pistillode in the male flowers vestigial or absent. Fruit an oblong-lanceolate or linear samara. Seeds flat, orbicular or obovate or ± triangular, exalbuminous.