Wastebasket taxon

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 often old (and perhaps not described with the systematic rigour and precision that is possible in the light of accumulated knowledge of diversity) and populous.

Sometimes, during taxonomic revisions, a wastebasket taxon can be salvaged after doing thorough research on its members, and then imposing tighter restrictions on what continues to be included.

[citation needed] A related concept is that of form taxon, "wastebasket" groupings that are united by gross morphology.

This is often result of a common mode of life, often one that is generalist, leading to generally similar body shapes by convergent evolution.