Trees, shrubs or hygrophilous herbs. Leaves opposite, rarely alternate, exstipulate, subsessile or sessile, simple, entire. Flowers actinomorphic or rarely zygymorphic, hermaphrodite, perigynous, 4-6-merous, bracteate, often bracteolate. Hypanthium usually ± campanulate or tubular, persistent. Epicalyx often present. Sepals triangular or ovate, valvate, persistent. Petals inserted at the top of the hypanthium, usually corrugate, sometimes minute, fugaceous or absent. Stamens inserted on the hypanthium, as many as, twice as many as sepals or numerous. Ovary 1-4-locular; placentation axile or free central; ovules numerous; style usually filiform; stigma often capitate. Fruit a capsule. Seeds numerous.
An important anatomical feature is the occurrence of intraxylary phloem.
A family of 25 genera and about 550 species widely distributed, mostly tropical and temperate. Represented in Pakistan by 7 genera and c. 13 species.
Acknowledgements: We are grateful to the United States Department of Agriculture for financing this research under P.L.480. Thanks are also due to Messrs B.L. Burtt, I. Hedge, and Miss J. Lamond of the Royal Botanic Garden, Edinburgh, for their helpful suggestions.