Delayed Self-Pollination as the Primary Reproductive Strategy in Cypripedium shanxiense S. C. Chen: Observations From...

Studying the pollination biological characteristics of the rare and endangered plant Cypripedium shanxiense S. C. Chen will provide a scientific basis for formulating conservation strategies for the species. This study investigates the flowering phenology, pollination insects, and the process of pollination and fruiting of C. shanxiense at the Beijing Songshan National Nature Reserve. The results indicate that the flowering period of C. shanxiense is 12-16 days. The full bloom period extends from early June to late June, with the population flowering duration lasting about 24 days. Four days after flowering, the pollen changes from a mucilaginous to a liquid state and flows to the stigma under the force of gravity. C. shanxiense exhibits high self-compatibility and can produce seeds through self-pollination, with a natural seed setting rate of 70%. Lasioglossum zonulum was observed visiting flowers and capable of carrying away pollen; its size traits related to pollination function are well matched with the flower structure of C. shanxiense, but its visiting frequency is extremely low. Overall, delayed self-pollination is the primary pollination method for C. shanxiense, rather than insect-assisted pollination.