厚朴居群叶表皮毛的显微特征差异及分类意义

Comparison of characteristics of leaf trichomes in Houpoёa officinalis and their taxonomical significances

关键词:  厚朴, 天然居群, 叶表皮毛, 显微特征, 分类意义

Key words:   Houpo&#235  a officinalis, leaf trichomes, microscopic characters, classification significance

摘要:

叶片的微观形态特征包括表皮的毛被特征,在现代植物分类研究中被越来越多地应用于疑难类群的分类鉴定中。厚朴为我国常用中药,该分类群的分类地位一直存在着很大争议。该研究选取16个厚朴的天然群体,运用光学和电子显微镜观测不同居群厚朴叶片的毛被特征,并通过对显微特征的UPMGA聚类分析,了解其分类地位及亲缘关系。结果表明:不同居群厚朴叶表皮毛差异显著,表皮毛各特征均呈现出多态性。16个居群厚朴叶表皮大致可以分为两类形态,一类由2～3个细胞组成,表皮毛直立或微倒伏,长147.48～489.21 μm,顶细胞长度远长于其他细胞,与其他细胞的衔接方式为直接; 另一类表皮毛由2～7个细胞组成,弯曲或扭曲,全长251.70～489.21 μm,顶细胞长176.47～353.23 μm,与其余细胞形成一定的夹角(123.31°～150.61°),顶细胞与其他细胞的衔接方式以钝接为主。16个样本可以分为两个类群——直立型和弯曲型,所划分的类群与根据叶形划分的类型基本一致。直立型表皮毛又可以划分为粗短型和细长型,所划分的类群对应的叶形为小凸尖型的厚朴和中间型厚朴。因此,该研究结果证实厚朴在归并为一个种后,将其分为3个地理亚种是合理的。

Abstract:

Cortex Houpoëa officinalis is a traditional Chinese medicine. There have been long disputes in classifying status in this taxonomic group. In this study, microphotography and scanning electron microscope were used to observe leaf trichomes of this taxonomic group of 16 natural populations. The result indicated that there existed significant differences in leaf epidermal hair among 16 populations, which indicated high polymorphism between populations. Microscopic structures of epidermal hair could be divided into two groups. One kind of epidermal hair was composed of 2-3 cells, upright or flattened a little, 147.48-489.21 μm long. The first cell was much longer than other cells, and comprises 79%-91% of the whole hair length. The connection pattern to other cells was boxer. The another kind of epidermal hair was composed of 2-7 cells, bent or twisted, 251.70-489.21 μm long. The first cell was 176.47-353.23 μm long, which comprised 65%-82% of the whole hair length and bearing angle of 123.31-150.61 to other cells. The connection pattern to other cells was obtuse angle. According to UPMGA clustering analysis of morphological diversity among populations, the hair of H. officinalis could be divided into two main groups, namely upright group and bent group. The result was basically coincident with Leaf-shaped. Meanwhile upright group can also be divided into two groups, namely leptosomatic group and stubby group, corresponding to typical H. officinalis and middle type. Therefore, the results prove that it is reasonable that H. officinalis should be divided into three geographic clans.