Variability in leaf surface features and water efficiency utilisation in C₃ and C₄ forms of alloteropsis semialata (R. Br.) hitchc.

Abstract

Alloteropsis semialata (R. Br.) Hitchc. occupies a unique position both taxonomically and physiologically in the Gramineae in that C₃ and C₄ photosynthetic and anatomical forms exist within a single taxonomic species. Both forms have been collected from a single ecological niche in the Transvaal highveld. This study shows further morphological and anatomical differences between the two forms with respect to stomatal size, and frequency of distribution, as well as differing epidermal cell characteristics. In addition physiological differences between the two forms are established with regard to photosynthetic rates, transpiration rates, and boundary layer and stomatal resistances. The C₄ form was found to be more efficient with respect to water utilization efficiency.