Evergreen trees, shrubs or rarely perennial herbs, without milky sap, monoecious or dioecious. Leaves simple, opposite or alternate, 5(-3)-nerved, entire, rarely dentate, coriaceous. Inflorescence of axillary cymose fascicles, racemes or spikes. Flowers minute, unisexual rarely bisexual, actinomorphic, hypogynous, bracteate; female flowers often pedicellate and larger than the male. Sepals 4(-6), biseriate, basally connate, imbricate. Petals absent. Stamens as many as sepals, antisepalous, anthers large, dithecous, dehiscence longitudinal or valvular. Carpels 3, rarely 2 or 4, syncarpous; ovary superior, rudimentary or absent in male flowers, 3-locular, rarely 2 or 4-loculed; placentation axile; ovules 1 or 2 in each locule, pendulous, anatropous with dorsal raphe; styles as many as carpels, basally connate or free and diverging, persistent, stigmas decurrent. Fruit a loculicidally dehiscent capsule or indehiscent fleshy drupe. Seeds with or without caruncle, endosperm fleshy, embryo straight.
A small family of 4 genera and about 100 species; distributed in tropical and temperate regions; absent from Polynesia, Australia and Eastern South America. 2 genera and 3 species are reported from Pakistan.
The family was treated as tribe Buxeae of Euphorbiaceae by most authorities, for example Bentham and Hooker (Gen. Pl.3:242.1883), J.D.Hooker (Fl.Brit.Ind. 5:267.1885), although its separate identity was established much earlier by Dumortier (Comm.Bot.54.1822) on the basis of the absence of milky sap, styles free from the base, ovules with dorsal raphe. Baillon (Monogr.Bux.et Styloc.1859) and Muell.-Arg. in DC. (Prodr. 16(l):7.1869) were the first to follow Dumortier in recognising its separate identity as a family.
Acknowledgements: We are grateful to the United States Department of Agriculture for financing this research under P.L.480. Thanks are also due to Mr. B.L.Burtt, Mr. I.C. Hedge and Miss J.Lamond of the Royal Botanic Garden, Edinburgh and Dr. N.K.B.Robson of the British Museum (Natural History), London for their helpful suggestions.