Structural characteristics and eco-adaptability of heteromorphic leaves of Populus euphratica

Abstract

The microstructural and ultrastructural traits of three kinds of typical leaves of Populus euphratica Olive, including lanceolate, broad-ovate and dentate broad-ovate leaves, were studied by using electron microscope and optical microscope. The results showed that with the leaves changing from lanceolate shape to dentate broad-ovate shape, their structure obviously tended to be xeromorph: developed palisade tissue, undeveloped spongy tissue, thick cutin layer and sunken stomas. The amount of mitochondria tended to be increased, and the shape of chloroplasts varied from regular spindle to irregular rotundity or oval. The leaves were covered with wax without cilium, and the stomas on the upper and lower epidermis of the leaves opened unevenly. The stomas on the lower epidermis were deeper than those on the upper epidermis under the scanning electron microscope. The results implied that the structural characteristics of the diversiform-leaves of P. euphratica are related to its eco-adaptability.