25种广义花楸属(Sorbus)植物叶脉序特征研究

Study on Venation Characteristics of 25 Sorbus Species

目的:探索叶脉序特征在花楸属(Sorbus)植物分类上的意义。方法:以25种花楸属植物的腊叶标本为材料,通过制作叶脉序标本及对叶脉序特征进行聚类分析。结果:25种广义花楸属植物的一级脉均为羽状脉;二级脉为达缘脉或半达缘脉,粗二级脉间距分为规则、不规则、向基部渐减3种类型,细二级脉有或无,间二级脉无,或每个二级脉区间通常为1条、每个二级脉区间多于1条和每个二级脉区间少于1条;二级脉间三级脉对生贯穿、互生贯穿、混合贯穿或网状;四级脉不规则网状、对生贯穿和互生贯穿或混合贯穿,脉间区发育分为差、中和良3种,游离端小脉末端不分支、简单分支、二歧分支或不均等分支;根据叶脉序特征进行聚类分析,可将25种花楸属植物分成4组。结论:花楸属植物的叶脉序特征可为属下植物的分类提供新的研究资料。

Objective:Exploring the significance of leaf venation characteristics in the classification of Sorbus plants. Methods:25 species of Sorbus were used as materials to make venation specimens and cluster analysis of venation characteristics. Results:The primary veins of all 25 species were pinnate.The secondary veins were craspedodromous or semicraspedodromous. The major secondary spacings were regular,irregular,or decreasing proximally. The minor secondary veins were present or absent. The intersecondary veins were absent,or generally one per intercostal area,or more or less than one. The intercostal tertiary veins were opposite percurrent,alternate percurrent,mixed percurrent,or reticulate. The quaternary veins were irregular reticulate,opposite percurrent,alternate percurrent,or mixed percurrent.The areolation development was poor,moderate,or good. The freely ending veinlet terminals were unbranched,simple branched,dichotomous branched,or dendritic branched. The 25 Sorbus species can be divided into 4 subgroups on the base of cluster analysis of vein order. Conclusion:The venation characteristics of Sorbus can provide new information for the classification of the plants under the genus.