Introduction

Abstract

Clusia minor L. is the most astonishing plant I ever had in my hands, and it offers fascinations much beyond the fact that Clusia is the only dicotyledonous tree genus with crassulacean acid metabolism (CAM) (Chap.1). C. minor shows all possible variations of CAM as well as full C₃-photosynthesis. Only C₄-photosynthesis is missing in this species as well as in the whole genus as far as this can be seen. However, the plasticity and flexibility of C. minor is so large that different modes of photosynthesis, C₃ and CAM, respectively, can be performed by two different opposite leaves at the same node and even by different parts of one leaf simultaneously (Chap. 8). C. minor displays all conceivable facets of CAM. It shows versatile dynamics of shifts between C₃-photosynthesis and CAM. Due to the longevity of its leaves for more than one season in C. minor these switches are reversible and can occur frequently and repeatedly, in contrast to the annual therophyte Mesembryanthemum crystallinum L. which is now very intensively studied and frequently considered the preferable model plant for C₃/CAM intermediate behaviour.