The
stamen (
plural stamina or
stamens, from
Latin stamen meaning "thread of the
warp") is the male
organ of a
flower. Each stamen generally has a stalk called the
filament (from Latin
filum, meaning "thread"), and, on top of the filament, an
anther (from
Ancient Greek anthera, feminine of
antheros "flowery," from
anthos "flower"), and
pollen sacs, called
microsporangia. The development of the
microsporangia and the contained
haploid gametophytes, (called
pollen-grains) is closely comparable with that of the microsporangia in
gymnosperms or heterosporous
ferns. The pollen is set free by the opening (
dehiscence) of the anther, generally by means of longitudinal slits, but sometimes by pores, as in the
heath family (
Ericaceae), or by valves, as in the
barberry family (
Berberidaceae). It is then dropped, or carried by some external agent — wind, water or some member of the
animal kingdom — onto the receptive surface of the
carpel of the same or another flower, which is thus
pollinated.
Typical flowers have six stamens inside a perianth (the petals and sepals together), arranged in a whorl around the carpel (pistil). But in some species there are many more than six present in a flower (see, for example, the spider tree flower, below). Collectively, the stamens are called an androecium (from Greek andros oikia man's house). The anthers are bilocular, i.e. they have two locules. Each locule contains a microsporangium. The tissue between the locules and the cells is called the connective. In an immature, unopened flower bud, the filaments are still short. Their function is then to transport nutrients to the developing pollen. They start to lengthen once the bud opens.
The stamens of flowering plants contain often also microstructures lining the locules. Orbicules or Ubisch bodies are tiny sporopollenin particles that originate as lipid droplets within the tapetal cytoplasm.
The anther can be attached to the filament in two ways
