Cation accumulation and leaf succulence in Codonanthe macradenia J. D. SMITH (Gesneriaceae) under field conditions

Abstract

The development of leaf succulence and the content of K, Ca, Mg, P, and N were measured in the gesneriad Codonanthe macradenia J. D. SMITH, which grows as epiphyte in open sclerophyll forests on white sands in the Amazon basin (upper Rio Negro basin), under a wide range of light exposures. Leaves show a multiseriate adaxial epidermis occupying 35 %- 68 % of the total leaf thickness. Succulence and epidermis thickness are linearly correlated with the amount of K per unit leaf area, resulting in a nearly constant K concentration per unit tissue water. Both K and Pare more concentrated in the epidermis than in the underlying photosynthetic tissue. Succulence and K accumulation appears to be associated to N deficiency during leaf development. Succulence in this species may play an ecological role as a drought endurance mechanism.