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

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, ...

-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 (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately ...

, 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. 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 cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All ex ...

s, specifically '' Picea'' and '' Tsuga''.

References

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