玉叶金花属及其近缘属植物的叶脉序特征研究

Characteristics of leaf venation of Mussaenda and its relative genera

关键词:  茜草科, 玉叶金花族, 玉叶金花属, 叶脉序, 分类学, 聚类分析

Key words:  Rubiaceae, Isertieae, Mussaenda, leaf venation, taxonomy, cluster analysis

摘要:

玉叶金花属(Mussaenda L.)种间变异式样复杂,属内杂交现象突出,其分类一直备受争议。为探索玉叶金花属及其近缘属裂果金花属(Schizomussaenda Li)、假玉叶金花属(Psudomussaenda Wernham)叶脉序特征在属间及种间分类学意义,从而为其作为药用以及园林植物资源的鉴定、开发利用提供依据,该研究采用清净法制作叶脉标本,观察了22种该类群的叶脉序特征,基于叶脉序特征进行了聚类分析,并编制了分种检索表。结果表明:(1)玉叶金花属及其近缘属叶脉序特征具有一致性,一级脉都为羽状脉,间二级脉频度均为每个脉间区少于一条,粗二级脉与中脉夹角均为锐角,三级脉多为贯穿型,脉间区排列均不规则。(2)属间或属内种间有分类学价值的叶脉序特征为粗二级脉脉序类型、粗二级脉与中脉夹角、粗二级脉间距、粗二级脉与中脉连接方式、间二级脉及近缘二级脉的存在与否、三级脉贯穿类型、四级脉类型、游离端小脉分支情况、脉间区发育情况。(3)聚类分析显示该类群22种植物聚为12支,聚类分析中,裂果金花属及假玉叶金花属嵌入玉叶金花属内,显示了较近的亲缘关系。综上可知,玉叶金花属及其近缘类群的叶脉序特征可以为其分类提供新的研究资料。

Abstract:

The classification of Mussaenda L. has been controversial due to the complex interspecific variation and hybridization within the genus. In order to explore the taxonomical significance of leaf venation characteristics between Mussaenda and its relative genera(Schizomussaenda Li and Psudomussaenda Wernham), and to provide data for the identification, development and utilization when they were regarded as the medical and garden plant resources, the leaf venation characteristics of 22 species of this group were observed by using the cleaning method. The cluster analysis was carried out based on the characteristics of leaf venation, and a classification key of the species was compiled. The results were as follows:(1)The characteristics of the leaf venation of Mussaenda and its relative genera had consistency, which were mainly reflected on that the primary veins were all pinnate, the frequency of inter-secondary veins was less than one per areolation, the angles between the major secondary veins and the midveins were acute, the tertiary veins were mostly penetrating, and the arrangement of the areolation were all irregular.(2)The characteristics of the leaf venation with taxonomic value among genera or species within genera included the type of major secondary vein venation type, the angle between major secondary vein and midvein, the major secondary vein spacing, the connection between major secondary vein and midvein, the existence of inter-secondary vein and intramarginal secondary vein, the penetration type of intercostal tertiary vein, the type of quaternary vein, the branching of freely ending veinlet, and the areole development.(3)According to the cluster analysis, 22 species of this group were clustered into 12 branches, and Schizomussaenda and Psudomussaenda were not clustered into one branch respectively, showing a relatively close genetic relationship. In conclusion, the leaf venation characteristics of Mussaenda and its related taxa can provide new information for the classification of the plants.