Abstract: The ultrastructure and changes after hydration of pollen wall in Liriodendron chinense and L. tulipifera were observated by electron microscope. The results were shown follows: (1) The mature pollen wall consists of six layers which are exine sexine, nexine 1, nexine 2, inline 1, inline 2 and inline 3. (2) During hydration of pollen, new layer (pollen tube preparing layer) is formed be-tween intine 3 and vegetative cell plasma membrane by P-particles and coated vesicle. (3) When pollen germinates, pollen tube wall forms by protruding of part of intine 3 and new layer from germinating aperture. (4) Early stage of pollen tube differentiates into two layerspection outer lay-er which is dark and callose inner layer which is electron transparent.

Key words: Liriodendron

摘要： 观察描述了在电镜下中国鹅掌揪(Liriodendron chinense)北美鹅掌楸(L．tulipifera)2种植物花粉壁的超微结构及其水合后的变化。(1)成熟花粉壁由6层组成，即外壁3层—外层，中层1和中层2，内壁3层—内壁1，内壁2和内壁3。（2）花粉水合时，在内壁3与质膜之间由P-粒子（多糖-粒子）和被膜小泡参与形成新层。（3）花粉萌发时，由内壁3的一部分和新层突出萌发孔共同形成花粉管壁。（4）新层于花粉管形成早期分成2层—外染色深的果胶层和内电子透明的胼胝质层。

关键词: 鹅掌楸属, 花粉壁, 超微结构