Annual or perennial herbs or shrubs, monoecious or dioecious, often appearing silvery from a covering of collapsed bladder-like hairs, less commonly the hairs remaining inflated imparting a mealy appearance. Leaves mostly alternate. Flowers in axillary clusters or commonly clusters aggregated into spicate or racemose inflorescences. Male flowers lacking bracts or bracteoles; perianth 5-lobed; stamens 5. Female flowers generally lacking a perianth, but subtended by a pair of free or fused bracteoles which enlarge and cover the fruit at maturity; stigmas 2. Seed erect (sometimes horizontal in A. hortensis).
Over 250 species world-wide, often in saline habitats; c. 67 species in Australia, 7 naturalised, 1 also indigenous in New Zealand, the remainder endemic.