Basidiospores

Basidiospores are the sexual spores produced by Basidiomycota, a large fungal group that includes mushrooms, bracket fungi, puffballs and shelf fungi. They are formed on basidia, microscopic club-shaped cells located on the hymenium of a basidiocarp. Following karyogamy and meiosis within the basidium, haploid basidiospores are liberated and dispersed. Most basidia generate four basidiospores, but the exact number can vary among taxa; some produce two or eight spores per basidium.

Discharge and morphology: Basidiospores are commonly discharged ballistically, a forceful mechanism driven by surface tension and Buller's drop, enabling active spore ejection into the surrounding air to enhance wind dispersal. The spores are typically small, ranging from about 5 to 20 micrometers, and may be transparent or pigmented. Shapes are variable, including ellipsoidal or fusiform, and ornamentation on the spore surface occurs in many species.

Germination and life cycle: After landing on a suitable substrate, basidiospores germinate to form haploid hyphae. Compatible hyphae of opposite mating types can fuse to produce a dikaryotic mycelium, which develops into a fruiting body bearing basidia and restarting the cycle. Basidiospores are generally the primary means of dispersal for Basidiomycota.

Ecology and significance: Basidiospores enable wide geographic distribution and ecological diversity, including roles as wood decayers, mycorrhizal partners, and plant pathogens such as rusts and smuts. Spore morphology and coloration are commonly used in taxonomic identification alongside basidiocarp features.