High Productivity of Certain Agronomic CAM Species

Abstract

There are 25 to 30 flowering plant families that have species showing CAM (44). In some, CAM appears nearly exclusive, e.g. in the Crassulaceae and Cactaceae. In others, such as the Liliaceae and Asclepiadaceae, only the succulent species show CAM. The 10,000 or more angiosperms that show CAM (141) include over 1,000 of the bromeliads (64) and several thousand orchids. Thus, CAM metabolism overall is an important feature of photosyn? thesis in fluwering plants. There have been several reviews on CAM, and CAM was reviewed twice before in the Annual Review of Plant Physiology; first, by Ranson and Thomas In 1960 (90), and then by Osmond in 1978 (79). There is one monograph entitled Crassulacean Acid Metabolism, published in 1978 (44), and two proceedings from meetings, one in 1982 (122) and the other in 1984 (62). The objective of this present review is to summarize and comment on aspects of CAM studied since the last major reviews in 1978. No attempt will be made to cover the literature comprehensively.