In flowering plants, pollen is produced on male organs called stamens that sit at the center of the flower, usually surrounding the pistil (the female part). The stamens are composed of a long stalk, a filament, on which sits the anther--the bulbous organ that produces pollen. Pollen itself is a hard-surfaced grain that contains and protects the sperm cell.
Within the anthers, there are two or more loculi, which are tissues that are capable of forming pollen. On the inner side of each of these are large cells called the tapetum, which give nutrients to the new grain of pollen and surround it with a cell wall. Also within the loculi are pollenmothercells that divide to form the nucleus of the pollen grains.
Each of the pollenmothercells divide twice, forming four daughter cells, called spores. Once these have separated, the tapetum deposits the other wall that protects the spore from drying, bruising and ultraviolet damage. It may also deposit a sticky substance that helps the grain attach to insects and adhere to the pistil.
Ripening & Release
Next, the spore divides into large vegetative surrounding a smaller fertile cell. The tapetum continues to deposit material, resulting in a thick, sculptured cell wall. After drying for a few days, the pollen grains are freed through either pores or slits in the anthers.