Terminology

Abstract

Different terms have been used to describe the CAM phenomenon. In the English literature, the term Crassulacean Acid Metabolism is established and generally accepted because most species within the family Crassulaceae exhibit the phenomenon in a classical manner, and because Crassulacean plants were used in many of the initial fundamental studies. Unfortunately, the expression implies that CAM is restricted to the Crassulaceae, which is far from being true as will be shown later (see Chap. 1). In the German literature, often the term Diurnaler Säurerhythmus (i.e., Diurnal Acid Rhythm) is used, referring to the oscillation of malic acid content during the day/night cycle (see Wolf, 1960). This term has the advantage of neutrality in view of the taxonomic distribution of CAM plants, however, it does not exclude oscillations of acids other than malic which are not involved in CAM.