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.