Division Basidiomycota includes both edible and poisonous mushrooms, puffballs, rusts, smuts, and more, for a total of 25,000 species, about a third of known fungi species. Many play a vital role in the decomposition of litter, wood, and dung. Some, like chantarelle mushrooms, are quite good to eat and are highly prized for their flavor. However, other species like the smuts, attack crops and can cause economic devastation.

The basidiomycetes are united in the fact that they exist primarily in the dikaryotic stage, when two nuclei in the same cell do not fuse. Only in the basidum, a unique structure, does fusing occur to form a diploid nucleus.

There are a few characteristics that unite the division Basidiomycota. Two main ones, dikaryotic mycelium and a basidium for a meoisporangium, have been discussed above. Another uniting hallmark is that the cell wall is multilayered. This can be seen when the cell wall is ruptured, especially in budding yeast cells. Also, these organisms all form ballistospores. These spores discharge from the hypha, basidia, single yeast cells, or other ballistospores, and can fuse sexually or produce a new organism asexually.

The basidiomycetes are often seen in our daily lives. The best example of this is the mushrooms, which are the fruting bodies of the dikaryotic basidiomycetes. Members of division Basidiomycota rot our houses, and while they can cause corn smut and other agricultural problems, mychorrhizae, members of this group, provide plants with nutrients in a symbiotic relationship and helped the colonization of land by the plants.

Fungi have been used as a food source since the beginning of recorded history. Mushrooms add flavor, texture, and nutritional value to many dishes. In North America in recent years, a variety of mushrooms have gained popularity, including portabella, cremini, oyster, morel, chantarelle, wood or tree ear, truffle, matsutake, and shiitake. Truffles--tuber-like, fleshy fungi with a characteristic taste and aroma--are highly prized by gourmet chefs. Harvested most commonly in France and northern Italy, truffles are collected with the aid of trained dogs or pigs that use scent to hunt these fungi hidden beneath the soil. The price for truffles in Europe may reach as high as $500 (U.S.) per pound in some years.

Bracket fungi, one class of Basidiomycetes, are familiar in woodlands, where they cause the rapid decay of stumps and fallen trees and shrubs. Many species, however, also grow on living trees (or even telephone poles or lumber), causing white or brown rots that often kill the trees. A few members of the family feed on decaying matter in the soil. Most bracket fungi are annuals that produce new basidiocarps each year, although some are perennials that produce another layer of tubes each year and may last for several years. One edible species of bracket fungus is the tuckahoe.

There is evidence that division Basidiomycota is monophyletic and consists of three main groups. The basic difference in this group is between the Urediniomycetes and the rest of the division. The other two groups, the Ustilaginomycetes and the Hymenomycetes, have been proved to be very closely related because they have similar septal pores, spindle pole bodies (in mitosis and meiosis), cellular carbohydrates, and rRNA.