锦鸡儿属花粉形态及其分类意义

POLLEN MORPHOLOGY AND ITS TAXONOMIC SIGNIFICANCE OF CARAGANA FABR.(FABACEAE)FROM CHINA

在光学显微镜和扫锚电镜下对锦鸡儿属31种2变种植物花粉形态进行了观察。根据外壁表面纹饰,可分:类型Ⅰ,表面具小穿孔;类型Ⅱ,具网状纹饰。在类型Ⅱ中据网眼大小和网脊宽度特征又分为两个亚类型。根据花粉体积大小,可分4个类型。本属植物花粉形态较为一致,表明是一个自然类群。组、系的花粉形态特征与一般形态变异不一定相对应,即形态上有明显区别的种类,在花粉形态上未必有很大区别,仅一些种类及矮锦鸡儿系Ser.Pygmaeae的花粉形态相近。本属花粉形态在种下等级的变异,特别是青藏高原分布的种类的变异较为明显,例如C.bicolor,C.jubata,C.erinacea与各自的近缘种类。花粉形态为分类处理提供了参考。本属植物花粉形态是从表面具小穿孔向具网状纹饰演化,对应于羽状叶类群向掌状叶类群演化。

Pollen grains of thirty-one species and two varieties of the genus Caragana Fabr. were observed under LM and SEM. The results revealed that the pollen exine ornamentation of the species examined could be divided into two types perforate and reticulate. The later, type consists of two subtypes according to lumina size and muri width. In the first subtype the lumina is round with diameter equal to muri width,and the exine is perforate in two polar areas, while in the second subtype lumina is irregular or polygonal, with diameter smaller than muri width. The pollen volume was divided into four types. The genus Caragana is a natural group which was indicated by the general resemblance of pollen morphology. In this genus the pollen morphological classification was not in concordance with the arrangement of the sections and series except Ser. Pygmeae and some species. The pollen variation at infraspecific level was obvious, especially the species distributed in Qinghai-Xizang Plateau, such as C. jubata, C. tricolor and C. erinacea . The evolutionary trend of pollen morphology is from perforate to reticulate, which is congruous with the evolution from the pinnate leaf group to the palmate leaf group in the genus.