松属针叶角质层微形态特征在分类学中的应用

Application of Cuticular Micromorphology of the Cuticle of Pinus Needles in Taxonomy

角质层是表皮细胞壁表面的一层不透水的脂肪性物质。角质层与表皮细胞紧密结合,植物表皮细胞形态和排列方式、气孔器的形态结构等微形态特征均能在角质层上反映出来。利用光学显微镜和扫描电镜对松属(Pinus)12种植物针叶角质层微形态特征进行观察和比较,详细描述20个性状,其中12个性状来自角质层内表面,8个性状来自角质层外表面。结果表明,这些特征可为该属属下分类和相似种的鉴别提供有用信息,具有重要的分类学意义:(1)表皮细胞长度、表皮毛长度、角质层外表面起伏程度、表皮细胞轮廓、有无气孔塞和针絮状物质等角质层微形态特征具有自身特异性,在属下可作为松属组级水平上的分类依据。角质层微形态特征不支持将五针松组(P.Section Cembra)和白皮松组(P.Section Parrya)合并为P.Section Quinquefolius的观点,亦不支持将油松组(P.Section Pinus)分成P.Section Pinus和P.Section Trifolius的看法。(2)白皮松(P.bungeana)针叶角质层微形态特征既与五针松组有相同之处,又与油松组有相似之处,还有部分特征显示出不同于松属其他种类的独特性,可为白皮松亚属(P.Subgenus Parrya)的建立提供新依据。(3)扫描电镜下表皮细胞垂周壁纹路,气孔塞有无和外表面气孔形状等特征可为形态相似种火炬松(P.taeda)和湿地松(P.elliottii)提供种间界定依据。

The cuticle is an impermeable fatty layer on the surface of the epidermal cell wall,and closelycombined with epidermal cells,the micromorphological characteristics such as the morphology and arrangementof plant epidermal cells,as well as the morphological structure of the stomatal apparatus,can be reflected inthe cuticle.In this paper,the cuticular micromorphology of needles of 12 species of Pinus was observed andcompared by optical microscope and scanning electron microscope,and 20 characters were described in detail,of which 12 characters came from the inner surface of the cuticles and eight characters from the outer surface ofthe cuticles respectively.The results showed that these characters had taxonomic importance for the intra-genusclassification and the identification of similar species:(1)Micromorphological features of the cuticle such as thelength of epidermal cells,the length of bristle,the undulating degree of the outer surface of the cuticle,theoutline of epidermal cells,the presence or absence of stomatal plug and needle-like substances had theirspecificities,which could be used as a basis for the classification of Pinus at the section level.The micromorphological features of cuticles did not support the view of merging P.Section Cembra and P.SectionParrya into P.Section Quinquefolius,nor did it support the view of dividing P.Section Pinus into P.SectionPinus and P.Section Trifolius.(2)The cuticle micromorphological characteristics of the needles of P.bungeana were partly the same as P.Section Cembra,partly similar to P.Section Pinus,and partly different from otherspecies of Pinus,which could provide a new argument for the establishment of P.Subgenus Parrya.(3)Underscanning electron microscope,the anticlinal wall pattern of epidermal cells,the existence or nonexistence ofstomatal plug and the stomatal shape of the outer surface could provide interspecific delimitation basis formorphologically similar species of P.taeda and P.elliottii.