The pollen–ovule ratios, pollen fertility rate, pollen viability and longevity, pollen histochemistry of Calligonum mongolicum flowers were determined in the field by the middle reaches of Heihe River. The main results were as follows: Calligonum mongolicum is completely fertile and has starchy pollen. Anthers matured heterotypically. The pollen longevity was about 10h. The pollen viability was higher than 70% at the beginning of anthesis on sunny days. No difference in the pollen production of single anther was found between different flower morphes, but significant difference was in that of single flower. The pollen-ovule ratios of different morph flowers were 1625±125, 1750±177, 1500±102, 1563±120, 1875±72. Pollen–ovule ratios (P/O) reveal that C. mongolicum is facultative autogamous.

The pollen–ovule ratios, pollen fertility rate, pollen viability and longevity, pollen histochemistry of Robinia pseudoacacia flowers were determined in the field on Zhen Mountain in Yantai, Shandong province in China. The main results were as follows: Robinia pseudoacacia is completely fertile and has starchy pollen. The pollen longevity was about 80h. The pollen viability was higher than 90% at the beginning of anthesis on sunny days. 80h later, most pollen grains lose their viability. Pollen–ovule ratio (P/O) is 192±19. Accoring to Cruden, R. pseudoacacia is facultative autogamous.