The stamen (plural stamina or stamens) is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium.
A stamen typically consists of a stalk called the filament and an anther which contains microsporangia. Most commonly anthers are two-lobed and are attached to the filament either at the base or in the middle area of the anther. The sterile tissue between the lobes is called the connective. A pollen grain develops from a microspore in the microsporangium and contains the male gametophyte.
The stamens in a flower are collectively called the androecium. The androecium can consist of as few a one-half stamen (i.e. a single locule) as in Canna species or as many as 3,482 stamens which have been counted in Carnegiea gigantea. The androecium in various species of plants forms a great variety of patterns, some of them highly complex. It surrounds the gynoecium and is surrounded by the perianth. A few members of the family Triuridaceae, particularly Lacandonia schismatica, are exceptional in that their gynoecia surround their androecia.
Depending on the species of plant, some or all of the stamens in a flower may be attached to the petals or to the floral axis. They also may be free-standing or fused to one another in many different ways, including fusion of some but not all stamens. The filaments may be fused and the anthers free, or the filaments free and the anthers fused. Rather than there being two locules, one locule of a stamen may fail to develop, or alternatively the two locules may merge late in development to give a single locule. Extreme cases of stamen fusion occur in some species of Cyclanthera in the family Cucurbitaceae and in section Cyclanthera of genus Phyllanthus (family Euphorbiaceae) where the stamens form a ring around the gynoecium, with a single locule.