Systematical unit ( taxonomy).

Important fungal classes are ascomycetes, zygomycetes, and basidiomycetes, important pteridophyte classes are club mosses, equisetaceae and ferns, important angiosperm classes are one class of monocotyledonous and two classes of dicotyledonous plants. In the case of animals there are for example various classes of fishes, as well as the classes of amphibia, reptils, birds, and mammals.