Pollen-Bearing Pumpkin Blossom
Many plants bear pollen and ovule on separate blossoms, so that self-fertilization is impossible. They are said to be dioecious. This picture shows a pumpkin blossom with the modified and coalesced stamens at its center bearing a quantity of pollen. The insects in visiting the blossom carry the pollen on their bodies or feet and transfer it to other flowers.
This image is from: Luther Burbank: his methods and discoveries and their practical application. Volume 3 Chapter 3