Stomatal Density in Leaves of Various Xerophytes: A Preliminary Study

Recent general botany and plant anatomy textbooks state that stomatal density of xerophytic leaves is higher than that found in leaves of mesophytes. In contrast, previous textbooks indicate that stomatal density in xerophyte leaves is reduced. The purpose of this study is to examine the leaves of succulent and non-succulent xerophytes to determine if opposite trends in stomatal density correlate with the xeromorphic strategy employed. The species examined were the succulents Crassula argentea, Kalanchoe blossfeldiana, K. diagremontiana, K. tubiflorum, and the non-succulents Nerium oleander, Ammophila breviligulata, and Ficus elastica. Stomatal densities of succulents were determined directly from epidermal peels. Stomatal densities of non-succulents, whose stomates occur in crypts, were determined from cross-sections using stereo logical methods. Results indicate that stomatal density is reduced in leaf succulents and increased in non-succulent types