A study of the variation in the essential oil and morphology of Pelargonium capitatum (L.) L’Hérit. (Geraniaceae). Part III. Geographical variation in essential oil composition and floral structure

Pelargonium capitatum (L.) L’Herit. is one of the parent species oi the cultivar Rose grown on the Island of Reunion for its essential oil. The ultimate aim of this project is to identify chemotypes which could be included in hybridization programmes to ennoble the cultivar Rose. Forty populations of P. capitatum were selected along the west and east coasts of South Africa to describe the essential oil and macromorphological diversity in relation to geographical distribution. A multivariate statistical analysis was performed on the essential oil data. A survey of the composition of the volatile oils proved the species to display high levels of essential oil variation which allows for the species to be divided into chemotypes correlating to geographical distribulion. No clear-cut macromorphological discontinuities were apparent between populations, but an obvious congruence between the essential oil composition and macro-morphology was accentuated in extreme cases.