Annual or perennial herbs or shrubs, rarely trees, often more or less succulent. Leaves usually alternate, sometimes opposite, diverse in shape, often fleshy and terete or reduced to scales, exstipulate. Flowers small, hermaphrodite or unisexual, solitary or in clusters or in spicate or paniculate inflorescences, often supported by bract and two bracteoles, actinomorphic. Perianth greenish, whitish or (rarely) coloured, persistent, of 3-5 free or connate tepals, rarely 0, unchanged or accrescent in the fruiting stage, sometimes with wing-like projections or appendages. Stamens 1-5, opposite perianth segments, usually free, rarely united at base into a cup-like ring, sometimes reduced into staminodes between fertile stamens. Ovary usually superior, free, rarely adnate to perianth, with a single basal ovule; styles 2, rarely 3-5, free or united at base. Fruit one-seeded, mostly indehiscent, rarely dehiscent. Seeds horizontal or vertical (sometimes both positions at one individual); embryo straight, bent, or circular around perisperm or spiral. Endosperm absent; perisperm abundant or lost.