Anatomical Structure of Vitex negundo L.var.heterophylla (Franch.) Rehd. Leaves and Its Ecology Adaptation

The paraffin slices of Vitex negundo L.var.heterophylla(Franch.) Rehd.leaves were observed under light microscope.The results showed that the leaves of Vitex negundo L.var.heterophylla(Franch.) Rehd.had typical morphological characteristics of xerophytes.It had typical bifacial leaf composed of epidermis,mesophyll and vein.The cells of both upper and lower epidermis were monolayer and arranged closely and tightly.The outside cell wall of upper epidermis had cuticle and a little trichome(glandular and nonglandular).The lower epidermis had much more trichomes and most of them were unglandular.There were lots of chambers under stomata in lower epidermis.The mesophyll was strong and riched in chloroplast.The mesophyll tissue differentiated obviously with 2-3 layers of palisade tissue,more than the 3 layers,and irregular-shaped spongy tissue arranged loosely with large gap among cells.The xylem in the midrib of vein was strong,while the vascular bundle in the lateral vein simplified gradually.The characteristics mentioned above were suitable for drought circumstances.