Pollen grains, illustration. Pollen grains are the male sex cells of a flowering plant. Under the microscope pollen displays an endless array of fascinating shapes with all manner of textures and features. Many of these unique adaptations are to help the pollen get where it needs to go, namely, its own species' female counterpart. Surface features help grains cling to different modes of transportation, such as bird feathers, bee legs or animal fur. Pollen is produced in such quantities that it is a significant component of the airborne particles in Earth's atmosphere, especially over continents. The proteinaceous substance in many pollen grains induces an allergic reaction commonly known as hay fever.