Pollination efficiency
Our field surveys showed that there were five pollinator species ofH. mutabilis during our experiments. To compare the pollen removal, pollen deposition, and pollination efficiency of various pollinator species, more than 200 flowers of H. mutabilis were selected randomly from different individuals and were bagged with fine-mesh polyester bags before blooming in October 2023. When the flowers bloomed, all flowers were exposed to pollinators. When the flowers had been visited a single time in the field, we harvested the flowers immediately. To estimate pollen grains deposited on the stigmas of the flowers, each stigma was dissected and washed in 5 mL of 75% alcohol to dislodge the pollen grains from the stigma. The suspension was stirred for 2 min, and the sample of suspension was drawn on the plankton counting chamber, after which the number of pollen grains in the sample was counted under a light microscope at ×10 magnification. Moreover, we counted pollen grains remaining in the anthers of the flowers following the methods described above. Pollen removal per flower was calculated as the mean number of pollen grains per flower minus the remaining grains per flower. Finally, pollination efficiency was calculated by dividing pollen deposition by pollen removal.