Abstract:In order to explore the influence of habitat on the micromorphology of Selaginella plants, we used a scanning electron microscope to comprehensively observe the morphological characteristics of lateral leaves, middle leaves, fertile leaves and microspores of seven Selaginella species collected in Qixianling, Hainan, and measured and calculated stomatal size, stomatal density, spore size. Differences in micromorphology and the relationship between micromorphology and habitat were compared and analyzed to provide a reliable basis for the classification of Selaginella species. Results show that: (1) lateral leaves, middle leaves and fertile leaves of the same species of Selaginella have obvious differences in leaf epidermal morphology, especially the stomata on fertile leaves are smaller and sparer than those of sterile leaves, which is consistent to the reproductive function of fertile leaves. (2) The leaf epidermis characteristics of different species of Selaginella are also distinct, mainly in leaf margin thorns, stomata and tumorlike bulges, indicating that these characteristics can be used as the basis for the distinction between species of Selaginella. (3) The microspores of Selaginella are stable in morphology and diverse in texture; the microspores in some species are similar in shape, but are distinguished by the type of ornamentation and the curvature of cracks. (4) The microspores of S. hainanensis have a unique mesh pattern, suggesting that it has a unique evolutionary pathway. (5) The stomata characteristics and the knoblike bulging characteristics of the leaf epidermis of Selaginella, the color and the ornamentation of microspores are related to the elevation and the moisture of habitat, but the mechanism needs further study.