Walters, S.M. et al. (eds) (1997) The European Garden Flora. Vol. V. Dicotyledons (Part III). Cambridge University Press, Cambridge
Description of the genus
Shrubs. Leaves alternate, simple, entire, toothed or palmately lobed. Flowers solitary or in few-flowered racemes or cymes. Epicalyx segments present, 6-16. Calyx irregularly lobed. Corolla red, funnel-shaped.
Staminal column with 5 teeth at apex. Styles and stigmas 10.
Fruit a schizocarp with 5 mericarps.