Physiological Anatomy of Nonsucculent Leaves

Abstract

Many long-standing explanations for anatomical adaptations of desert plants and xerophytes can be traced to a classic analysis of Egyptian desert plants (Volkens 1887). This work proposed principles for desert botany and set the tone for explaining each anatomical feature of a desert photosynthetic organ as an adaptation primarily designed for water conservation. Volkens was correct to emphasize the gas diffusion pathway in his analysis, but overlooked the potential value of these anatomical features for determining rates of CO₂ diffusion. The modern approach, which must challenge many often-cited explanations in the literature, attempts to interpret the relative significance of each parameter affecting water vapor and CO₂ as independent fluxes with over-lapping, but not identical, diffusion pathways (Nobel 1991a; Jones 1992).