Basidiomycete

Basidiomycetes are a major group of fungi within the phylum Basidiomycota. They comprise a diverse range of forms, from large fruiting bodies such as mushrooms and bracket fungi to puffballs and rusts. A defining feature is the basidium, a club-shaped cell on which basidiospores are produced externally after meiosis. Most basidiomycetes spend much of their life as a filamentous, septate mycelium, and in many species a sexual fusion of compatible hyphae gives rise to a dikaryotic mycelium that later forms fruiting bodies.

Sexual reproduction typically begins with plasmogamy, the fusion of two compatible hyphae, followed by the establishment of a dikaryotic stage. Karyogamy occurs within the basidia, producing diploid nuclei that immediately undergo meiosis to form haploid basidiospores, which are dispersed to start new mycelia. Basidia are often arranged on gilled, poroid, or smooth surfaces of the fruiting body, where they bear spores externally.

Ecologically, basidiomycetes are key decomposers of lignocellulosic material, particularly wood. They also include ectomycorrhizal species that form mutualistic associations with trees and plant pathogens such as rusts and smuts. Economically and ecologically important basidiomycetes include edible mushrooms (for example, Agaricus bisporus and Pleurotus ostreatus), producers of industrial enzymes, and species used in bioremediation. Some basidiomycetes produce potent toxins, such as amatoxins in several Amanita species.

Diversity estimates place described species around 30,000, with total diversity likely much higher. Basidiomycetes occur worldwide, from forests to grasslands, and play central roles in nutrient cycling, plant health, and food systems.