10种金花茶组植物的花粉形态及分类学意义

Pollen morphology and taxonomic significance of ten species of sect. Chrysantha

关键词:  金花茶组, 扫描电镜, 外壁纹饰, 花粉形态, 分类学

Key words:  sect. Chrysantha, scanning electron microscope, exine ornamentation, pollen morphology, taxonomy

摘要:

金花茶组(Sect. Chrysantha)植物具有很高的观赏价值,但其分类存在争议。为探讨金花茶组植物花粉的形态特征和分类学意义,该研究用扫描电镜观察了10种金花茶的花粉形状、外壁纹饰以及穿孔特征,统计了极轴长、赤道轴长和萌发沟长,并进行聚类分析。结果表明:(1)10种供试金花茶植物花粉为中粒花粉,大部分花粉形状呈近球形,仅有东兴金花茶为扁球形及凹脉金花茶为长球形; 花粉的外壁纹饰可以分为脑纹状纹饰、拟网状纹饰和疣状纹饰三类,不同种花粉表面穿孔大小和密度存在明显差异。(2)聚类分析结果显示10种金花茶可以分为4大类:四季金花茶、中东金花茶、金花茶以及显脉金花茶的花粉形态较为相近; 淡黄金花茶、中越山茶、小花金花茶、东兴金花茶的花粉比较相近; 而凹脉金花茶和毛瓣金花茶的花粉形态与其他金花茶区别较大。金花茶组植物花粉的外壁纹饰和穿孔状况各异,结合极轴、赤道轴以及萌发沟长等特征可区分10种供试金花茶。从孢粉学角度来看,金花茶组植物的花粉具有山茶属植物的一般特征,不具有特异性,该组植物可能不是一个独立类群,但其花粉形态存在明显种间差异,可以作为分类学依据。该研究结果可为金花茶组植物种间分类提供依据。

Abstract:

Species of sect. Chrysantha have high ornamental value, but their classifications are controversial. In order to study the morphological characteristics and taxonomic significance of pollen in sect. Chrysantha, we observed morphological shape, exine ornamentations and perforation characteristics of 10 species of sect. Chrysantha pollen grains by scanning electron microscope, and the polar axis, equatorial axis and length of germination groove were analyzed by clustered. The results were as follows:(1)The pollen of sect. Chrysantha was medium-sized and most of them were subspherical, only C. indochinensis var. tunghinensis was oblate sphere and C. impressinervis was prolate; The extine ornamentation of pollen could be broadly divided into three types: tuberculate-baculate, ornate and verrucate, and the size and density of surface perforation were obviously different.(2)Cluster analysis showed that the pollen morphology of C. perpetua, C. petelotii var. grandiflora, C. petelotii and C. euphlebia were proximity; C. flavida, C. indochinensis, C. micrantha and C. indochinensis var. tunghinensis had similar characteristics; However, C. pubipetala and C. impressinervis were clearly different from the others. The extine ornamentation and perforation of pollen were different, but it was still necessary to combine the polar axis, equatorial axis and the length of germination groove to clearly distinguish the 10 species of sect. Chrysantha. From the perspective of palynology, the pollen of sect. Chrysantha has the general characteristics of Camellia without specificity, and this group plants may not be an independent group, but the pollen morphology of this group plants has obvious inter-specific differences, which can be used as the basis for taxonomy. The results of this study provide the basis for the taxonomic status among species of sect. Chrysantha.