Amaranthus
20 species in Aust. (5 native); all states and territories
Erect to prostrate, usually monoecious, annual herbs. Leaves alternate, entire. Flowers unisexual, small, with a bract and 2 bracteoles at the base, in axillary or terminal clusters or spikes which often form a dense panicle. Perianth segments 3–5, green or scarious. Stamens 3–5, free. Styles 2–3. Fruit a nut or capsule , enclosed in the persistent perianth. Seed solitary, black, glossy.