Description from Flora of China
Trees or shrubs, deciduous, with latex; monoecious or dioecious. Winter buds with 3-6 bud scales; scales imbricate. Stipules free, sublateral, caducous. Leaves alternate; leaf blade simple to deeply palmately lobed, margin toothed; primary veins 3-5 from base, secondary veins pinnate. Male inflorescences axillary, spicate, many-flowered, shortly pedunculate. Female inflorescences shortly spicate to capitate. Male flowers: calyx lobes 4, imbricate; stamens inflexed in bud; pistillode top-shaped. Female flowers: sessile; calyx lobes 4, imbricate, fleshy in fruit; ovary 1-loculed; style present or not; stigma 2-branched, abaxially pubescent or papillose. Fruit with enlarged, succulent calyx usually aggregated into juicy syncarp. Syncarp with achenes enclosed by enlarged and succulent calyx; endocarp shell-like; exocarp fleshy. Seed ± globose; endosperm fleshy; embryo incurved; cotyledon elliptic.
Morus species are cultivated in many temperate and tropical countries. The leaves are used as food for silkworms and the fruit for human consumption. Male material is often very difficult to name.
Morus calva H. Léveillé is Coriaria sinica Maximowicz (Coriariaceae) and M. mairei H. Léveillé is Acalypha mairei (H. Léveillé) Schneider (Euphorbiaceae).
About 16 species: widespread in all temperate areas, also in the mountains of tropical Africa, Indonesia, and South America; 11 species (five endemic, one introduced) in China.