What is the very common name for the male sex cells in plants?

In the intricate world of plant reproduction, the transfer of genetic material is accomplished by microscopic structures known as pollen grains. Each tiny grain is essentially a protective vessel containing the male gametes, or sex cells, of a seed-producing plant. These are produced in the anther, which is the part of the stamen (the male floral organ) that sits atop a slender stalk. For fertilization to occur, a pollen grain must travel from the anther to the receptive stigma of a flower's female organ, a process called pollination.

The journey of these grains is a marvel of natural engineering. Some plants, like grasses and many trees, produce vast quantities of lightweight pollen designed to be carried for miles on the wind. This is the type most often responsible for seasonal allergies. Other plants have evolved to use animals as couriers; their stickier, heavier pollen adheres to bees, birds, and butterflies as they move from flower to flower seeking nectar. The incredibly tough outer shell of a pollen grain not only protects it during its travels but also allows it to be preserved for millions of years, providing scientists with a fossil record of ancient ecosystems.