Trees or shrubs, in Mal. evergreen or almost so, usually containing very bitter substances. Twigs pithy. Hairs mostly simple and 1-cellular, sometimes glandularcapitate. Leaves (in Mal.) spirally arranged, simple or 1-pinnate, often articulated, often provided beneath (rarely also above) with pitted, concave, or flattish glands (in Mal. in Ailanthus, Brucea, Samadera, and Soulamea). Stipules usually absent, (in Mal.) present in Irvingia and Picrasma. Inflorescences usually compound, axillary, rarely terminal; plants monoecious, rarely dioecious. Flowers usually small, actinomorphic, uni- or bisexual, or functionally unisexual. Sepals 3-5, almost always partly connate, valvate to slightly imbricate. Petals 3-5, free, imbricate or valvate, rarely absent (in extra-Mal.), or united into a tube (extra-Mal.). Stamens inserted at the base of the disk, isomerous or dimerous, rarely numerous (extra-Mal.), mostly obdiplostemonous, rarely the stamens of the outer whorl doubled, not rarely with a scale at the inner base; anthers 2-celled, opening lengthwise, introrse to latrorse, versatile. Disk intrastaminal, often gynophorous, sometimes rather inconspicuous, at least when dry. Ovary often 2-5-lobed, 1-5-celled, or with free carpels; styles 1-5. Ovules 1-2 (in Mal. 2 only in Suriana), axile, anatropous (in Harrisonia and Suriana amphitropous). Fruit(s) usually indehiscent often drupaceous, sometimes a samara, some carpels sometimes aborted. Seed: endosperm 0 or scant; cotyledons planoconvex; embryo straight or curved; no aril. Distribution. About 30 genera, with c. 200 spp. with the main centre in tropical America, and a second centre in tropical West Africa. With the exception of Picrasma quassioides (D. DON) BENN., ranging as far north as North Japan and Korea, and of Ailanthus altissima (MILL.) SWINGLE, which is endemic in subtropical to temperate China, the species of this family are native in the tropics. The monotypic genus Suriana has the widest range and is almost pantropical along sandy beach, being absent only on the west coast of Africa.