sterigmata

Sterigmata are slender cellular projections found on the basidia of many basidiomycete fungi. They are the structures from which basidiospores develop and are ultimately released. Each sterigma extends from the upper portion of a basidium and terminates at the point where a spore is formed.

In a typical basidium, several sterigmata arise, and a single basidiospore is produced at the distal end of each sterigma. The most common arrangement is four sterigmata per basidium, corresponding to four spores, but the number can vary among species—from two to several sterigmata. Sterigmata can be simple, slender filaments or more robust, slightly curved projections, and their length and morphology may influence how spores are oriented during discharge.

During development, basidial formation gives rise to sterigmata, and meiosis occurs to produce haploid basidiospores at the tips. When mature, spores are released from the sterigmata, aiding dispersal into the environment.

In taxonomy, the presence, number, and shape of sterigmata are characters used to distinguish groups of basidiomycetes and to describe the morphology of basidia in different taxa.

Etymology: The term derives from Latin sterigma, meaning a small stem or stalk.