Description from Flora of China
Shrubs or trees. Branchlets terete or 4-angled, glabrous or pubescent. Stipules small, filiform, caducous. Leaves opposite, petiolate; leaf blade punctate, pinnately veined, with intramarginal veins. Inflorescences axillary and 1-3-flowered dichasia, racemes, or thyrses, sometimes terminal and paniculate. Flowers bisexual or sometimes staminate, 3-5-merous, often fragrant; bracteoles often small, sometimes caducous. Hypanthium globose, urceolate, or obconiform. Calyx lobes sometimes subequal, persistent. Petals pink or white, punctate. Stamens numerous, in several series; filaments filiform; anthers globular, dorsifixed, dehiscing by longitudinal slits; connectives usually terminating in an apical gland. Ovary 3-13-loculed, placentation axile; ovules 1-2[-4] per locule, collateral. Style filiform; stigma capitate or peltate. Fruit a berry, globular, vertically ribbed, usually 1- or 2-seeded per locule. Seeds separated by a vertical false septum; seed coat and pericarp separate; testa bony; embryo horseshoe-shaped; radicle long; cotyledons short.
Specimens of Decaspermum have flowers that are either perfect or staminate, but it is unclear whether plants with staminate flowers are andromonoecious or androdioecious.
The treatment and descriptions for Decaspermum are largely adapted from Scott (Kew Bull. 34: 59-67. 1979; 35: 403-411. 1980) except for more recently described species. The genus name "Pyrenocarpa" (Hung T. Chang & R. H. Miao, Acta Sci. Nat. Univ. Sunyatseni 1975: 62. 1975), which was not validly published because no type was indicated, was established on the basis of its possessing an 11-13-loculed ovary and fruit with a solitary ovule in each locule; however 9-loculed material of D. hainanense also has been observed. Given the variation in these characters elsewhere in Decaspermum (ovary 3-10-loculed, ovules 2-4 per locule), it is considered that the two Chinese species assigned to "Pyrenocarpa" are better included within the former genus.
About 30 species: SE Asia, Australia, Pacific islands; eight species (five endemic) in China.