Sorting fungi is no easy task. It is a very old group (over 540 million years old) and there are many doubts about its origin and evolution.
Below is a scheme with the classification of fungi and then the description of each group.
The chytridiomycetes, consisting of about 790 species, are the probable ancestors of the fungi. They live in the aquatic environment and in moist soils near dams, rivers and lakes. They live on the absorption of decomposing organic matter and often parasitize algae, protozoa, other fungi, plants and animals. Some species cause considerable damage to crop plants (alfalfa and corn).
The ascomycetes, with about 32,000 species, are the ones that form sexual reproductive structures, known as ascos, within which meiotic spores are produced, the ascospores. They include various types of mold, truffles, Morchellas, all filaments, and yeasts (Saccharomyces sp.), which are unicellular.
The basidiomycetes, with about 22,000 species, are the ones that produce sexual reproductive structures called basidia, producers of meiotic spores, the basidiospores. The group includes mushrooms, wooden ears, rust and coals, the latter two causes of plant disease.
The zygomycetes, with about 1,000 species, are fungi widely distributed in the environment, and can act as decomposers or as animal parasites. The best known is the Rhizobux stolonifer, a mold that grows on fruits, breads and sweets - its fruiting body is a white fluff that resembles cotton filaments, filled with dark dots that represent the sporangia.
The deuteromycetes, or conidial fungi, which have been known as imperfect fungi, constitute a group of fungi that do not fit the above. In many of them, the sexual phase is not known or may have simply been lost throughout the evolutionary process. In general, they reproduce asexually through the production of conidiospores. To this group belong several species of Penicillium (including the penicillin producer) and Aspergillus (some species produce carcinogenic toxins).