Perennial herb to 3 m tall, with rhizomes and tubers, hairy. Stems erect, often branched above. Leaves ovate to lanceolate, to 20 cm long, to 8 cm wide, margins toothed. Capitula few to many, to 8 cm across; mostly summer. Ray florets yellow. Disk florets yellow. Achenes 4-6 mm long, hairy. Pappus of 2 short bristles.
N and S America
In N America this was cultivated by the Indians before European settlement and was introduced to Europe in the 17th century and thence worldwide. The tuber contains the carbohydrate inulin, which breaks down to form fructose rather than glucose as occurs with common starch and is thus important for diabetics. Many of the commercial cultivars are unnamed but from the USA there are 'Vadim' and 'Volga'. Hybrids with sunflowers are also in production.
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.