Abstract: The pollen morphology and wall ultrastructure of Liriodendron chinense and L. tulipifera and their hybrids are investigated. The pollen ultrastructure differs between parents, and between hybrids and parents. From genetic analysis of the pollen structure of Liriodendron hybrids and parents, the structure changes gradually from smooth foveolate reticulate to rugulate verrucate in L.chinense→ L. tupilifera, original cross F1, and reciprocal cross F1. The pollen structure characters show patroclinal transgressive inheritance.