The relationship between CAM and leaf succulence in two epiphytic vines, Hoya carnosa and Dischidia formosana (Asclepiadaceae), in a subtropical rainforest in northeastern Taiwan

Abstract

Past reports of correlations between Crassulacean acid metabolism (CAM) and leaf succulence are based on multi-species comparisons. When different individuals of the same species were compared in two epiphytic CAM vines growing in a subtropical rainforest in northeastern Taiwan, the degree of CAM was not correlated with leaf thickness, a measure of succulence. Leaf chlorophyll (Chl) a and b concentrations and ratios correlated well with leaf succulence, indicating that differences in leaf succulence were likely a result of sun/shade adaptations, not photosynthetic pathway. These findings challenge the assumption that CAM-succulence correlations are causal. © Springer Science+Business Media B.V. 2009.