Taxonomy of the genus Pelargonium (Geraniaceae): the section Polyactium. 1. Circumscription and intrasectional classification

The historical subdivision of the section Polyactium DC. of the genus Pelargonium L’Herit. (Geraniaceae) was traced. This subdivision was re-assessed in view of new information that had become available since the last Intrasectional classification, as well as a better understanding of the taxonomical significance of floral and vegetative features. This resulted in the recognition of four subsections which are distinguished from one another by their floral (and in one subsection, vegetative) morphology. The subsections are circumscribed and a key to their identification is provided. Species excluded from the section are listed with reasons for their removal.