An insect-pollinated flower has to load pollen onto a visitor and then catch it again on the next flower. Which combination of features does that?
Explanation
Pollen that clings to an insect and a receiving surface that grabs it back again are a matched pair, and both are placed inside the flower where a visitor cannot avoid brushing them. Feathery receiving surfaces held out in the open are built to strain pollen from moving air, so they belong to flowers that never meet a pollinator at all.