Greek petasos — broad-rimmed hat, an apparent allusion to the large leaves.
Perennial herbs, rhizomes present. Stems erect, scape-like. Leaves mostly basal, simple, margins entire to palmately lobed, developing after inflorescences, long-petiolate. Capitula radiate, diskiform or diskoid, of 2 types on different plants, few to many in terminal panicles or racemes, stalked. Involucral bracts in 1 or 2 rows, overlapping,more or less equal. Receptacle flat.outer florets sterile or female, ligulate, 2-lipped or tubular, variously coloured. Inner florets sterile or functionally male, tubular, variously coloured. Achenes obloid, glabrous. Pappus of many fine simple bristles. [Petasitis Mill.]
One species has become naturalised in Australia.
Large, round, long-petiolate leaves; 2 types of capitula present on different plants.
About 19 species from Europe, Asia 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.