Anatomical Structure of Eighteen Species of Orthotrichum from Xinjiang

Here we provide evidence for the classification of Orthotrichum Hedw.in Xinjiang by observation on their anatomical structure.The characteristics included cross-section of stem and leaf and stoma types,with the stems and leaves of 18 species of Orthotrichum transected by free hand section.The cross-section of the stem was composed of epidermis and cortex,with no central strand differentiation.The leaf monostratose were recurved,with simple or branched papillae per cell except Orthotrichum hallii Sull.et Lesq.The characteristics such as the color of the stem and leaf cross-section,the proportion of epidermis and cortex,papillsity,shape of costae cross-section,width of the costae and cells set,and gemmae morphology were valuable for the classification of the species with the same stoma type.The taxonomic key to the 18 species was developed based on the above characteristics.