中国西南地区独活属植物叶表皮微形态特征及其系统学意义

Leaf Epidermal Morphology and Systematic Significance of Genus Heracleum in Southwest China

利用光学显微镜和扫描电镜对中国西南地区独活属16种1变种植物(分隶于中国独活属的全部4个组)的叶表皮微形态进行了观察,测量并统计气孔器大小、密度和气孔指数,并用统计学方法对远轴面气孔器长轴进行显著差异性分析。结果显示:无规则型气孔器普遍存在于所有研究类群的叶远轴面及个别类群叶近轴面,气孔器的分布和密度具有种间特异性。表皮毛普遍存在于远轴面及大部分类群近轴面,长短和覆盖密度因种而异。近轴面表皮细胞为多边形或者不规则形,垂周壁平直、浅波状或波状;远轴面表皮细胞形态多不规则形,表皮细胞垂周壁浅波状或波状。在扫描电镜下,叶表皮气孔器外拱盖内缘为近平滑、浅波状或波状;角质膜条纹状,有的附有颗粒状、鳞片状蜡质等结构。气孔器外拱盖形态以及蜡质类型是稳定的鉴别特征。研究表明独活属植物叶表皮特征存在较大的种间差异,对独活属的系统分类及进化研究具有重要意义,文中对叶表皮特征在独活属植物分类处理中的应用及系统进化问题等进行了讨论,并建立了以叶表皮微形态特征为依据的分类检索表。

Leaf epidermis characters in 16 species 1 variety（belonging to all the four sections） of Heracleum（Apiaceae） in SW China were investigated using light microscopy（LM） and scanning electron microscopy（SEM）.The stomatal size,density and index were measured,and the statistical t-test method was used to ascertain the significant level of the differences in the stomata of each species.It was shown that the stomata were anomocytic and existed on the abaxial epidermis in all the species examined,and on the adaxial epidermis in a few of species.The length and density of the trichomes vary with the species and presented on abaxial epidermis of most studied species and on the adaxial epidermis of some species.The adaxial epidermis cells were usually irregular or polygonal in shape with anticlinal walls straight,repand,or sinuous,and the epidermal of abaxial epidermis cells were usually irregular in shape with anticlinal walls repand,or sinuous.Under SEM,the inner margin of the outer stomatal rim was nearly smooth,repand or erose,and the cuticular membrane of the leaf epidermis was stripe,covered with granular or squamose wax.The types of outer stomatal rim and wax were reliable characters to identify some species.These data of leaf epidermis of Heracleum demonstrated that there are many distinct characters among the species.We discussed the systematic and evolution significance of leaf epidermis,and a dichotomous key of Heracleum according to leaf epidermis characters was also compiled in this paper.