Commelinidae is a botanical name at the rank of subclass. Circumscription of the subclass will vary with the taxonomic system being used (there are many such systems); the only requirement being that it includes the family Commelinaceae. A well-known system that did use this name is the Cronquist system (1981), but it was also used by the Takhtajan system:
In the Takhtajan system treats this as one of six subclasses within the class Liliopsida (=monocotyledons). It consists of