Carbon isotope ratio measurements of succulent plants in southern Africa.

Succulent plants representing 16 families and a variety of growth forms originating from winter, summer, and year-round rainfall regimes in southern Africa were analyzed for carbon isotope ratios. Most families had species with δ13C values indicative of CAM, particularly those from winter and year-round rainfall regimes. Plants with δ13C values intermediate between CAM and C3, indicating flexible photosynthetic pathways, were generally leafy perennials subject to seasonal tissue dehydration. Reproductive tissue tended to have less negative δ13C values than vegetative tissue on the same plant, indicating drought-season origin of the former.