Leaf Comparative Anatomy of Styrax(Styracaceae) in Hunan

Abstract

The leaf epidermal micromorphology and anatomical structures of ten species in the genus Styrax from Hunan province in China were examined and statistically analyzed under light microscopy and scanning electron microscopy( SEM). The results were as follows:( 1) The epidermis was composed of a single layer of cells which are polygonal or irregular in shape and their anticlinal walls are straight,arched,or sinuous;( 2) The size and density of stomata apparatus between species are significantly different;( 3) The inner margin of the outer stomatal rim of stomata apparatus is nearly sinuolate or sinuous,and the cuticular ornamentation around stomata apparatus is characteristically distinguished by the bird's nest-like cuticular ornamentation of S. tonkinensis and the bowl-shaped cuticular ornamentation of S. suberifolius;( 4) The T-shaped thickening at either polar region of stomatal guard cells is found in S. hemsleyanus,S. dasyanthus and S. faberi;( 5) The upper epidermis of S. suberifolius and S. macrocarpus was composed of large cells;( 6) The mesophyll was differentiated into palisade parenchyma and spongy parenchyma,and the thickness of palisade parenchyma and spongy parenchyma and the ratio of palisade to spongy thickness are distinctly different among species. The palisade parenchyma of S. tonkinensis is differentiated into two layers;( 7) The main vein vascular tissues constitute a closed ring structure in S. macrocarpus and S. odoratissimus but an open semicircular structure in other species. The leaf epidermal micromorphology and anatomical structures can be used as an important basis for the identification and classification between species of Styrax,which is of some taxonomic significance.