The stamen is the male reproductive organ of an angiosperm, like a flower, and it consists of the anther and filament. The filament is a stalk that acts as the support for a sac it bears called an anther. The anther is a sac where pollen grains develop. The pollen grains house the angiosperm’s sperm. The Red Bougainvillea, which is pictured above, has multiple stamens surrounding a single carpel, the female reproductive organ of an angiosperm.