中国蔷薇属植物叶表皮微形态特征及其系统学意义

Micromorphological characteristics of leaf epidemis and systematic significance of Rosa L. from China

关键词:  叶表皮, 气孔器, 蔷薇属, 微形态, 系统学意义

Key words:  leaf epidemiss, stomatal apparatus, Rosa L., micromorphology, systematic significance

摘要:

应用光学显微镜和电子显微镜,对30种中国蔷薇属植物叶表皮的微形态特征进行了观察。结果表明:叶表皮细胞一般为多边形或不规则形,垂周壁平直、平直弓状、波状、浅波状和深波状式样; 该属植物的叶表皮细胞大小种间差异较大,总体来看上表皮几乎全为多边形细胞,且上表皮细胞比下表皮细胞略大; 在扫描电镜下观察,大部分细胞的平周壁下陷,仅部分细胞的平周壁突起; 叶表皮角质层纹饰多样、即使同一个种的上下表皮细胞角质层纹饰微形态特征也有差异; 大多植物叶片表面具柔毛,均为单毛,有长柔毛和短柔毛,大部分种类的柔毛基部无特化,其基部由普通的表皮细胞围绕着,少部分种类的柔毛基部由几个特化的辐射状细胞围绕着,少数植物无毛; 有些植物叶表面或叶脉上还分布有腺毛; 除了单叶蔷薇亚属的小蘗叶蔷薇1个种的上下表皮均分布有气孔器外,其余蔷薇亚属的29种植物的气孔器均分布在下表皮,形状为椭圆形、宽椭圆形和长椭圆形三种,气孔器类型有无规则型、不规则四细胞型、对位四细胞型、环列型和辐射型; 气孔器外拱盖内缘近平滑或呈深浅不同的波状、气孔器外拱盖纹饰光滑或粗糙,大多植物气孔器的保卫细胞两级T型加厚; 另外,只有小蘗叶蔷薇的气孔器具双层外拱盖且仅上表皮被毛等特征也说明了其在演化上的特殊地位,蔷薇属植物叶表皮的这些微形态特征,在属内各组间无明确的规律性,但可为探讨该属种间的分类学及亲缘关系提供依据。

Abstract:

The micromorphological characteristics of leaf epidemis of 30 Rosa L. species from China was observed by using light microscope and scanning electron microscope(SEM). Both the adaxial and abaxial epidermal cells were polygonal or irregular in shape with anticlinal walls undulate or straight and arched. The size of leaf epidermal cells has greater interspecific difference in general. The upper epidermal cells of the genus were almost all polygonal and the upper epidermal cells were slightly larger than the lower epidermal cells. Periclinal walls of most epidermal cells of the genus were sunken and some fraction of epidermal cells were bulging under the scanning electron microscope. All 29 plants of the subgen. Rosa L. were hypostomatic except for amphistomatic R. berberifolia belonging to subgen. Hulthemia. Most stomatal types were anomocytic with some others anomotetracytic or paratetracytic as well as stomatal shape elliptic, widely elliptic or oblong elliptic. Inner margin of outer stomatal rim were nearly smooth or sinuolate, or with sinuous and sinuate, besides, ornamentation of outer stomatal rim were smooth or nearly smooth or with scaly waxy layer with most stomata apparatus “T” type thickening of guard cells poles. Two kinds of trichomes were distinguished in this study. They were pubescence or glandular in Rosa L., and most species had long pubescence or short pubescence, as well a small number of plants were glabrous. Bases of most single pubescences had no specialization and were surrounded by ordinary epidermal cells. Only a very small group of species were surrounded by specialized radial cells. The cuticular wax ornamentation were nearly smooth, papillose or granulate, or with layer of small processes and flake-like waxy layer. All the observed species of the subgen. Rosa L. were unilaminar outer stomatal rim except for R. berberifolia belonging to subgen. Hulthemia and that R. berberifolia also had trichomes in just the upper epidermis. So R. berberifolia belonged to subgen. Hulthemia had a special position in evolution, which was also explained by the research results of this paper. There were no clear regularity in the micro morphological characteristics of the leaf epidermis of Rosa L. in each group within the genus, but it can provide the basis for systematic taxonomy and phylogenetic relationships between species, and leaf epidermis characters can be used to differentiate similar species that were easily confused with each other. The significance of these epidermal features was discussed.