The Ascomycota or sac fungi are a diverse group with huge numbers of species. They play an essential ecological role, because they attack and digest resistant molecules such as cellulose and lignin of plants and collagen of animals. All Ascomycota can reproduce asexually. In sexual reproduction compatible mating types conjugate, a capsule called an ascus forms. Be aware that the cell size of yeast is so tiny that they can be mistaken for prokaryotes, except they have organelles that you should be able to see.
Some species are hallucinogenic, and many are toxic.
In sexual reproduction hyphae of opposite mating types conjugate, and ultimately spores are formed. The mushroom form of fruiting body is called a basidiocarp and consists of a stem and cap. Basidiospores, basidia, and gills may be seen in detail. These so-called imperfect fungi have no known sexual stage, and thus assignment to the divisions above is not possible. Many kinds of sac and club fungi have a symbiotic association with photosynthetic cyanobacteria or algae.