The stamen (
plural stamina, 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"),
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). They are positioned just below the
gynoecium. 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.
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