Pollen germination in pyrus species and species hybrids

Pollen germination in most Pyrus species was moderately high, usually averaging above 50 per cent. Five species were completely or nearly pollen sterile: P. nivalisJacq., P. ovoideaeRehd., P. Decaisne, P. salicifolia, var. pendula and P. variolosaWall. Microspores appear plump and normal following microsporogenesis. Degeneration of pollen grains occurred in the post-meiotic phase of pollen maturation.