In biology, a sterigma (: sterigmata) is a small supporting structure. It commonly refers to an extension of the

basidium A basidium (: basidia) is a microscopic spore-producing structure found on the hymenophore of reproductive bodies of basidiomycete fungi. The presence of basidia is one of the main characteristic features of the group. These bodies are also ...

(the

spore In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...

-bearing cells) consisting of a basal filamentous part and a slender projection which carries a spore at the tip. The sterigmata are formed on the basidium as it develops and undergoes

meiosis Meiosis () is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, the sperm or egg cells. It involves two rounds of division that ultimately result in four cells, each with only one c ...

, to result in the production of (typically) four nuclei. The nuclei gradually migrate to the tips of the basidium, and one nucleus will migrate into each spore that develops at the tip of each sterigma. In less common usage, a sterigma is a structure within the posterior end of the genitalia of female

Lepidoptera Lepidoptera ( ) or lepidopterans is an order (biology), order of winged insects which includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organ ...

. It also refers to the stem-like structure, also called a "woody peg" at the base of the leaves of some, but not all

conifer Conifers () are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a sin ...

s, specifically ''

Picea A spruce is a tree of the genus ''Picea'' ( ), a genus of about 40 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal (taiga) regions of the Northern hemisphere. ''Picea'' is the sole genus ...

'' and ''

Tsuga ''Tsuga'' (, from Japanese (), the name of '' Tsuga sieboldii'') is a genus of conifers in the subfamily Abietoideae of Pinaceae, the pine family. The English-language common name "hemlock" arose from a perceived similarity in the smell of it ...

''.

References

{{Insect-anatomy-stub Fungal morphology and anatomy Plant morphology Insect anatomy