旋花科牽牛屬的花粉形態

Pollen Morphology of the Ipomoea (Convolvulaceae) in Taiwan

本文研究以光學顯微鏡檢及掃描式電子顯微鏡檢觀察臺灣的18種牽牛屬植物的花粉形態，其特徵為球形、多孔、具刺紋及顆粒狀突起。但依據細微的外壁特徵，此屬可分為二群：第一群包括銳葉牽牛等10種，具有刺紋和圓柱體組成的六角形網脊圍繞在孔外圍區域，有明顯的網紋。第二群包括野牽牛等8種，不具孔外圍區域和六角形網脊，沒有網紋的分布。另外利用外壁及刺紋的特徵製作臺灣的牽牛屬花粉檢索表。

Pollen of 18 species of Ipomoea in Taiwan was examined in LM and SEM. Light microscope study of pollen morphology has shown that all examined species share common pollen morphological characters - spherical shape, pantoporate apertures and tectum with spinulate processes. On the basis of exine stratification, two different groups of this genus were defined : The Group 1 pollen include I. acuminata and 9 other species, possess spines, extraporal regions and tetragonal to hexagonal areas . The pores are surrounded by an extraporal region, and the spines and the ridges of the bacula form a tetragonal to hexagonal area around each extraporal region . Each pore is covered with an operculum which is peeled off after acetolysis. Fine reticula are present all over the surface of the grain. The reticula consist of very minute lumina. The Group 2 pollen include I. obscura and 7 other species. The extraporal regions and tetragonal to hexagonal areas are absent. Minute lumina are also present all over the surface of the grain. A key for distinguishing Taiwan's various species of Ipomoea, based on exine stratification and spinal characteristics, was made.