Perennial herb to 2 m tall, hairy. Stems erect, little-branched. Stem leaves to 12 cm long, palmately 3- or 5-lobed,margins toothed, sessile. Capitula in dense panicles, to 5 mm across; summer to autumn. Florets red or mauve, sometimes white. Achenes about 3 mm long, black.
Europe
E. album L. from E USA is a hairy perennial herb to 1 m tall with simple toothed leaves, small capitula in corymbs and with white florets. [E. glandulosum Kunth.]
E. purpureum L., Trumpet Weed, Joe Pye Weed, from the E USA is a mostly glabrous, purplish perennial herb to 3 m tall with simple toothed leaves in whorls, small capitula in corymbs or panicles, and pink, yellowish or purplish florets.
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.