Grewia tembensis Fresen and Grewia trichocarpa Hochst. ex A.Rich. (Grewioideae Hochr; Malvaceae Juss.) Micromorphological Study and Comparison via Electron Microscopy

Grewia tembensis and Grewia trichocarpa inhabit dry tropical zones and arid environments, adapting to extreme climatic conditions and limited moisture supplies. Overall, Grewia L. possesses a significant variety of bioactive chemical constituents of great therapeutic importance. Indeed, for these species, precise morphological analyses are poor, and their detailed characterization is almost non-existent. This research attempts to investigate and compare the micromorphological traits of G. tembensis and G. trichocarpa species through scanning electron microscopy (SEM). Micromorphological characteristics of the leaf and fructiferous structures turned out to be highly effective in separating the two species, G. tembensis and G. trichocarpa, especially regarding the type, density, and distribution of trichomes on the lower and upper surfaces of the leaves, along with the stomatal and trichome types on the surfaces of the fruits. Statistical analyses using principal component analysis, t-tests, and hierarchical clustering conducted on micromorphological data of the leaves, flowers, and fruits showed considerable variation within samples of G. tembensis and samples of G. trichocarpa. On the basis of their morphological assessment characteristics, the samples of both species were distinct and clustered into separate groups. This study emphasizes the necessity of performing detailed morphological studies of species by means of an electron microscope and proves that the leaf features are important for separating species. Such morphological traits of trichomes would offer an efficient tool to distinguish the species. Within the findings, this suggests that such diagnostics are likely to be highly useful for species identification in Grewia, especially in cases where there are no fruits available.