Cimicifuga simplex has three pollination ecomorphs with different flowering phenology, flower sex expressions, and selfing rates. A previous study showed that strong protandry in hermaphrodite of C. simplex causes there to be seasonal minority sexes; for example, female ramets are advantageous in the first half of the flowering season and bloom then. That study, however, did not distinguish the three ecomorphs. We related seasonal sex ratio changes and pollinator environments. Morph I (mainly hermaphroditic and female ramets) had high pollinator quality and quantity. Fruit set of hermaphrodites was high throughout the flowering season. Morph II (hermaphrodite and andromonoecy) had low pollinator quality, and few pollinators visited near the beginning and end of the season. Morph III (hermaphrodite and high selfing rate) had very low pollinator abundance. The scarcity of male flowers in morph I is likely a result of the high pollinator quantity and quality. The high fruit set suggests that no pollen limitation existed. The low pollinator quality and quantity of the morph II population caused it to suffer from pollen limitation and may explain the absence of female ramets in this morph. The high selfing rate of morph III may be due to the extremely low pollinator abundance.