中国蒿属植物比较形态和解剖学研究 Ⅱ花粉形态

POLLEN MORPHOLOGY OF ARTEMISIA IN CHINA Ⅱ POLLEN MORPHOLOGY

摘要:

本文通过光学显微镜和扫描电镜，观察国产菊科蒿属２亚属７组５８种代表植物的花粉形态，结合有关资料以及菊科１２族、３０属代表植物花粉作比较、分析研究，取得以下结果：１．蒿属的花粉形态特征具有高度的一致性．主要体现在：花粉呈球形或近球形，极面观为三裂圆形，赤道面观为圆形或椭圆形．具三孔沟特征，外壁具明显的两层结构，外层比内层厚，外壁纹饰为退化的小刺，易与菊科其他属区别．２．根据花粉的外壁纹饰，蒿属花粉分为两大类和四个亚型．（１）Ⅰ型：刺基多皱褶，外延伸，排列多数紧密，少数疏松．刺之间多少有延伸的刺基相连．（２）Ⅱ型：刺基不延伸，为独立的刺，按刺间颗粒或近光滑，以及刺排列紧密与否又分为Ⅱ－１、Ⅱ－２、Ⅱ－３、Ⅱ－４亚型．３．蒿属花粉类型的变化可能是适应风媒传粉的结果．花粉的外壁纹饰为退化的小刺，与菊科中以虫媒为主的属的花粉外壁纹饰为长刺明显不同．在蒿属各类型（亚型）中，进化类群小刺越来越退化，刺间颗粒越来越少至无，刺的排列从密集到疏松．上述的花粉类型（亚型）与分布相关，即原始的类群为Ⅰ型，多分布在高海拔高纬度的干旱地区；在低海拔低纬度的湿润地区，多为后出现的进化种类．

Abstract:

Pollen grains of 58 species of Artemisia were observed under LM and SEM to verify the reliability of the classification of Artemisia species. The tricolporate pollen grains with reduced exine ornamentation of Artemisia species make them easy to be distinguished from species of other genera of Compositae. Based on exine ornamentation, the pollen grains of Artemisia can be divided into two types: type Ⅰ, the hasal part of spinule corrugate and extend, type Ⅱ, the hasal part of spinule nearly rounded. There are 4 subtypes in type Ⅱ. i.e. Ⅱ-1, with spinules arranged sparsely, interspinule granular, Ⅱ-2, with spinules arranged sparsely, but interspinules smooth, Ⅱ-3, with spinules arranged densely, interspinule granular; Ⅱ-4, with spinules arranged densely, but interspinule smooth. The results observed have proved useful in the study of systematics in Artemisia. The evolution trends and the affinity of sections in Artemisia are also discussed.