Classification of organisms that do not fit in other classifications
Collage of Protista, probably the best-known wastebasket taxon. The members have little in common apart from being Eukaryota that are not plants, animals or fungi i.e., not complex multicellular organisms.
Wastebasket taxon (also called a wastebin taxon,[1]dustbin taxon[2] or catch-all taxon[3]) is a term used by some taxonomists to refer to a taxon that has the purpose of classifying organisms that do not fit anywhere else. They are typically defined by either their designated members' often superficial similarity to each other, or their lack of one or more distinct character states or by their not belonging to one or more other taxa. Wastebasket taxa are by definition either paraphyletic or polyphyletic, and are therefore not considered valid taxa under strict cladistic rules of taxonomy. The name of a wastebasket taxon may in some cases be retained as the designation of an evolutionary grade, however.