Another woody hemiepiphyte with CAM: Havetiopsis flexilis SPRUCE ex PLANCH. et TR. (Clusiaceae)

The discovery of crassulacean acid metabolism (CAM) in woody hemiepiphytes of the genus Clusia (Clusiaceae) has highly stimulated research on the phys iology of these plants in the last decade, Our knowledge of the possible oc currence of CAM in other hemiepiphytic taxa, however, is still rather limit ed. The results of a recently published field study with Havetiopsis flexil is. member of another genus in the Clusiaceae, suggested that this species is an inducible CAM plant but lack of plant material had made a rigorous te st of this notion impossible. The present communication presents conclusive evidence from a laboratory study under controlled conditions that drought indeed induces CAM in H. flexilis, i.e. leads to a net CO2 uptake at night associated with an increase in organic acids. The observed changes are full y reversible. This finding implies that at least three of the approximate 4 0 genera of woody hemiepiphytes have the capacity to use CAM.