The outer wall ( extine ) of the pollen grain is often diagnostic ( see pollen ) and very resistant to decay 花粉粒外壁（花粉壁）通常为特异性的并很难腐烂。
2.
Most of local plate - nectarine , ornamental peach and weeping peach cultivars had simple extine pattern , which shows that they were original types 供试材料的花粉粒形状以椭圆形为主，且首次发现哈太雷品种的花粉粒呈为圆球形。
3.
Results showed that the pollen grain of p . mira , which is used as material by sem for the first time , was nearly elliptic in shape and the extine pattern was simply striped with no pores 结果表明，光核桃花粉粒的形态呈椭圆球形，其外壁纹饰呈简单的直纹平行型，无穿孔，是最原始的桃亚属植物野生种，未发现与栽培种有直接的关系。
4.
There are mat - shaped thickenings at the base of spines in the certain species of machilus . the most reliable characters for the delimitation of species are the features of the perforation , mat - shaped thickenings . the evolutional trends of the extine ornamentations in the pollen grains were discussed 小刺和瘤状突起光滑，一些花粉形态特征如小孔的有无、垫状突起的有无和形态差别的多样性可以作为种间鉴定的依据，对于现有的润捕属植物分组有一定的借鉴价值。
