A study on ecological anatomy of leaves in 7 broad-leaved evergreen plants

Ecological anatomy of leaves in 7 broad-leaved evergreen plants is studied in this paper. The results show that all plants share typical xerophytic features as follows: the leaf blades are all typical back-abdomen bifacial type,compared to the lower epidermis which formed by one layers of small cells. The upper epidermis were formed by one or two layers of bigger cells on which covered with thicker cuticle. There are many stomas distributed in lower epidermis,while the upper epidermis have not any stomas. The palisade tissue consists of many layers of cells that line up densely,and cells of the spongy tissue line up loosely and formed aerenchyma. Middle vein was comparatively developed with obvious mechanical tissues and transport tissue. There are some differences in the structure of winter and summer leaf blades in broad-leaved evergreen plants:the thickness of cuticle,palisade tissue and leaf blade of the winter leaves are all thicker than that of the summer leaves,while the density of stomas and transport tissue of the former are less or less developed than that of the latter. These differences in the structure of winter leaves and summer leaves (developmental plasticity) reflect the adaptation of broad-leaved evergreen plants to the two different completely habitats in winter and summer(time heterogeneity of habitat).