Latin matrix — womb, caries — decay, as one species was used to treat infections of the uterus.
Annual herbs, glabrous to hairy. Stems erect, branched. Leaves along stems, alternate, divided. Capitula radiate or diskiform, terminal, solitary or in corymbs, with stalks. Involucral bracts in 2 rows, overlapping, unequal. Receptacle pitted, conical. Ray florets female, usually ligulate, white. Disk florets bisexual, tubular, yellow. Achenes asymmetrical, slightly compressed, 5-ribbed, glabrous. Pappus a small, crown, an ear-like lobe or absent.
Two species have become naturalised in Australia.
Long-pointed receptacle; 5-ribbed, curved, glabrous achenes.
7 species from Europe, Asia, North Africa and North America.
Source: (2002). Dahlia. In: . Horticultural Flora of South-eastern Australia. Volume 4. Flowering plants. Dicotyledons. Part 3. The identification of garden and cultivated plants. University of New South Wales Press.