Abstract:

The results of eco_anatomical observations on the leaf blades of 5 dominant species in a mixed forest of Xiangshan Mountain, Huaibei, China, indicated that these species share some xeromorphic characteristics such as a developed epidermal cuticle or hairs, total_palisade or flourishing palisade tissue, and developed vascular tissue in middle vein. Ziziphus jujuba var. spinosa and Vitex negundo var. cannabifolia, the two dominant species widely distributed throughout Xiangshan Mountain, show great plasticity in their lamina structure in two aspects: 1) Within the same community, the lamina structure shows temporal developmental plasticity with leaves collected at the beginning of May being more characteristic of sun plants as compared to those in mid September; 2) In different successional community, lamina structure are indicative of environmental plasticity. The shrub_herb communities tend to have xeromorphic/sun leaves, shrub communities have xeromorphic/sun leaves, the sparse mixed forest has mesophytic/sun leaves, and the Platycladus orientalis forest has mesophytic/shade leaves. These differences in leaf anatomy reflect both the ability for plants to adapt heterogeneous habitats as well as differences in the environment of the different communities. The results of non_parameter correlation analysis showed that the lamina structure was influenced by many environment factors, with soil water content, relative humidity and wind velocity being the principle factors. Lamina anatomical characteristics, such as cuticle thickness of the upper epidermis, stomatal density, thickness of the palisade tissue, leaf thickness, xylem thickness and bundle thickness of the middle vein, all were negatively correlated to soil water content and relative humidity and positively correlated to wind velocity.

Key words: Leaf structure, Lamina structure, Leaf blades, Phenotypic plasticity, Ecological anatomy