Crassulacean acid metabolism in Kalanchoë species collected in various climatic zones of Madagascar: a survey by δC analysis.

The carbon isotope compositions of samples of Kalanchoë species collected at the natural stands in Madagascar were determined. The results suggest that all species of the genus Kalanchoë are capable of crassulacean acid metabolism. The observed δC values cover the whole range from -10 to -30‰. This high diversity of the δC values was found among the species of the genus as well as, in certain cases, within a single species. This suggest that the CAM patterns in Kalanchoë are generally very flexible. The δC values show a clear correlation with the climate of the habitats from where the samples derived. Values indicative of CO fixation taking place exclusively during the night were found in the dry regions of Madagascar, whereas δC values indicative of mixed CO fixation during night and day or of CO fixation entirely during the day are distributed in the humid zones.