Perennial or annual herbs with prostrate to ascending stems, rhizomatous or stoloniferous, or with erect branching stems, glabrous to hirsute. Leaves simple or appearing compound with 3–5 digitate or palmate, entire to lobed leaflets, lamina often c. orbicular in outline, peltate or cordate, margins entire, toothed or lobed, petiolate; stipules scarious. Inflorescence a simple umbel (sometimes head-like), or compound with paniculate or spicately arranged umbels; bracts present or absent. Flowers bisexual, or sometimes unisexual; sepals minute or absent; petals entire, more or less ovate, usually acute; nectary depressed. Fruit laterally compressed, more or less distinctly 5-ribbed, smooth or sculptured; carpophore undivided and persistent (annuals) or falling with mericarps (perennials).
Over 130 species, chiefly in tropical and temperate areas of the Southern Hemisphere; 41 species in Australia (but genus in need of review, 2 naturalised), mostly endemic.