The part of a flowering plant that produces pollen is called the anther, which is part of the stamen. The stamen is the male reproductive organ of the flower and consists of an anther atop a long filament. The anther usually contains four pollen sacs, which are responsible for producing pollen grains. Once mature, the anther splits open and pollen is released. Pollen is a tiny dust-like structure that is transferred to the pistil by the process of pollination.