Abstract:

This paper presents the leaf epidermal microfeatures of 29 Salix species examined under scanning electronic microscope. Our results shown that the wax layer of Salix can be further divided into 6 types, crust ( present in S . cardiophylla, S. exigua, S . matsudana, S. clathrata , S. flabellaris, S. sinica , and S. gordejevii), layers with raised granules( present in S. paralesia, S. babylonica, S. myrtillaceae, and S. lindleyana ), smooth film ( present in S . tetrasperma, S. pentandra, S. maccalliana, S. polaris, S. polyadenia, S. turczaninowii, and S. berberifolia ), granules ( present in S . brachista, S. rotundifolia), conicoids (present in S. magnifica, S. flabellaris, S. oreophilla, S. souliei, S. arctica, S. sinica, S. variegate, S. cheilophila, and S. gordejevii), and scale- like conicoids ( present in S. triandra, S. alatavica, and S. hastata). Among them, the subtype of cale- like conicoids and coicoids were found only in both subgenus Chamaetia and subgenus Salix , two relatively advance subgenera in the genus Salix , so we speculate that conicoide is probably an advanced microfeature. We also found the inner margin of outer stomatal ledge was mostly smooth and seldom sinuous, and the later was observed only in the alpine and arctic Salix species. The morphology and keratinized of outer stomatal ledge together with wax morphology were relatively constant and quite useful for distinguishing species with similar phenotypes, but little valuable in the discrimination at section or subgenus level.

Key words: Salix