Basidio

Basidio is the term used to refer to the basidium, a small, club-shaped reproductive cell found in the Basidiomycota, a major fungal phylum. Basidia are the microscopic cells on the hymenium of basidiocarps (mushrooms, brackets, puffballs, and related fruiting bodies) where basidiospores are produced.

In a typical basidium, meiosis follows karyogamy inside the cell, producing haploid basidiospores that are released from basidia via sterigmata, usually four per basidium, though variation exists (two- or eight-spored basidia).

Basidia develop from specialized cells in the dikaryotic stage after plasmogamy of compatible monokaryotic hyphae. The basidium serves as the site of sexual recombination and spore formation, enabling widespread spore dispersal.

Basidiomycota include many ecologically important organisms, such as wood-decaying fungi, shelf fungi, and many edible mushrooms as well as plant pathogens like rusts and smuts. Basidiospores released from basidia are carried by wind, water, or biotic vectors, enabling colonization of new substrates.

The term basidio is occasionally used informally as a shorthand for basidium or to refer to Basidiomycota-related features. The formal term for the structure is basidium; the group is Basidiomycota, whose life cycle features a prominent dikaryotic phase and a basidial stage of spore production. See also basidiospore, basidiocarp, Basidiomycota.