中国薯蓣属植物叶表皮微形态特征及其分类学意义

Micro-morphological Characteristics of Leaf Epidermis and Its Taxonomic Significance in Dioscorea from China

利用扫描电子显微镜(SEM)对中国薯蓣科薯蓣属7组31种1亚种2变种植物的叶表皮细胞、叶表皮毛、气孔器类型、气孔大小、气孔纹饰等叶表皮微形态特征进行了观察和比较研究,为薯蓣属内种间的分类界定及系统发育研究提供证据。结果表明:中国薯蓣属各组之间在叶表皮毛、叶表皮细胞和气孔等微形态特征存在较大的差异,但也呈现出一定的组间特异性规律,如:四至六边形的叶表皮细胞、气孔周围平直的垂周壁式样为根茎组植物所特有;丁字型毛组叶脉和叶肉细胞上覆盖大量特有的2叉T型表皮毛;复叶组的叶脉和叶肉细胞具相当密集的表皮毛;基生翅组和周生翅组的气孔器类型衍生出了三胞型;气孔旋转方向在各组中明显分化,在丁字型毛组、白薯莨组和周生翅组(多毛叶薯蓣除外)中为左旋,而顶生翅组、基生翅组和复叶组表现为右旋。研究表明,叶表皮微形态特征在薯蓣属植物中是较为稳定的演化特征,可以作为中国薯蓣属分类与鉴定的依据;据此推断薯蓣属中顶生翅组和周生翅组较为进化,根茎组是薯蓣属的分化中心;对薯蓣属中存在争议的种:盾叶薯蓣和小花盾叶薯蓣、穿龙薯蓣和柴黄姜、马肠薯蓣、多毛叶薯蓣以及白薯莨等进行了分类界定。

Micro-morphological characters of Dioscorea in China,including shape of epidermis, feature of tri- chome hair,type and size of stomata, ornamentation of periclinal wall,and so on,was observed and meas- ured using scanning electronic microscope （SEM）, to provide foundation for taxonomic delimitation and phylogenetic study of Dioscorea. The results show that there are significant differences in trichome hair, ep- idermis and stomata among sections of Dioscorea. However, each section has its special feature. Such as quadrilateral or hexagon of epidermis and straight type of anticlinal wall in Sect. Stenophora. D. esculenta which belongs to Sect. Combiliurn covers a lot of T type binary trichome on vein and mesophll. Sect. Botry- osicyos are with density trichome hair and tricytic stomata in Sect. Enantiophyllurn. Stomatal orientation is left in Sect. Cornbilium, Sect. Lasiophyton and Sect. Enantiophyllurn except D. decipiens. However it is right in Sect. Opsophyton, Sect. Botryosicyos and Sect. Shannicorea. The results indicate that micro-mor- phological characters of Dioscorea are relatively stable,which could be used as classification and identifica- tion of this genus in China. As a result, we conduct that Sect. Shannicorea and Sect. Enantiophyllum are more evolutionary,while Sect. Stenophora is center of variation of Dioscorea. The taxonomic treatments ofcontroversial species were discussed at last, such as, D. zingiberensis, D. sinoparviflora, D. nipponica ssp. nipponica , D. nipponica ssp. rosthornii , D. simulans, D. decipiens and D. hispida.