Alternanthera Forssk.

8 or 9 species in Aust. (3 introduced); all states and territories

Herbs with prostrate or ascending stems. Leaves opposite. Flowers bisexual, in axillary spikes, heads or clusters. Perianth segments 5, scarious, whitish, hardened after flowering. Stamens 5, connate at the base, 2–3 often without anthers. Style very short or none; stigma capitate. Fruit a nut, usually compressed.