Structures from which spores emerge as produced by and fungal .

A basidium is a as produced by a basidiomycete. The products of basidia are and the structures that generate basidia are known more formally as basdiocarps. Karyogamy occurs in the basidiomycete in the basidium.

The basidium carries four basidiospores arranged as though resembling clubs as in, roughly, and hence the nickname of basidiomycetes as "club fungi". The basidium itself, minus the spores, also resembles a club.