Herbs, sometimes woody at the base, or more rarely shrubs. Leaves usually opposite, more rarely alternate or verticillate, simple, entire, with or without stipules. Inflorescence an often bracteate ...
Endress, Peter K. 2010. Synorganisation without organ fusion in the flowers of Geranium robertianum (Geraniaceae) and its not so trivial obdiplostemony. Annals of Botany, Vol. 106, Issue. 5, p. 687.