Deciduous, unarmed trees, with gummy bark and soft white wood containing myrosin cells. Leaves large, alternate, 2-3 pinnate, imparipinnate; pinnae and pinnules opposite; stipules and stipulules lacking or reduced to stipitate glands at the base of the petiole or of the pinnae respectively. Inflorescence dense axillary panicles, hairy. Flowers white or white streaked with red, bisexual, zygomorphic. Sepals 5, united forming a tube borne on a very short hypanthium, lobes cup shap¬ed, unequal, deciduous, imbricate, petaloid, reflexed. Petals 5, free, unequal; posterior 2 smaller, lateral ascending, anterior one the largest. Disk lining the hypanthium, flat or saucer shaped. Stamens 5, functional, declinate, unequal in length, antipetalous, alternating with the same number of staminodes, inserted on the margin of the disk; filaments free, villous and thickened at base; anthers monothecous, dorsifixed, dehiscence longitudinal, forming a head through which style protrudes at dehiscence. Carpels 3, united; ovary oblong, stipitate, superior, curved, villous, unilocular with 3 parietal placentas; ovules numerous in 2 series, pendulous; style 1, tubular, slender, with a single truncate, stigma, perforated in the centre. Fruit an elongated capsule, rostrate, 3 valved, torulose, unilocular, corky or pitted within. Seeds large, 3 winged or wingless, exalbuminous; embryo straight; cotyledons 2, rarely 3, thick; radicle short.
A family with a single genus and about 10 species, native of old world tro¬pics, widely introduced.
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 of the Royal Botanic Gardens, Edinburgh, for his helpful suggestions.