Herbs or shrubs, farinose or glabrous, often whitish, with usually flat, opposite or alternate leaves, monoecious rarely dioecious. Flowers polygamous, usually unisexual, in terminal or axillary clusters, forming a spike-like or paniculate inflorescence, male flowers with usually 5 perianth segments and 5 stamens; pistillate flowers usually without perianth but usually enclosed within 2, free or partly united bracteoles (valves), rarely with 4-5-lobed perianth segments then bracteoles absent. Styles and stigmas 2. Utricle usually enclosed within bracteoles (valves), pericarp membranous, mostly free or almost so; seed usually vertical, rarely horizontal or pendulous (especially in those with perianth), often dimorphic, smooth.