They may describe some characteristics of the group in general or may be a name already in existence before regularised scientific nomenclature.
Descriptive names above the rank of family are governed by Article 16[1] of the International Code of Nomenclature for algae, fungi, and plants (ICN), which rules that a name above the rank of family may either be ‘automatically typified’ (such as Magnoliophyta and Magnoliopsida from the type genus Magnolia) or be descriptive.
Descriptive names of this type may be used unchanged at different ranks (without modifying the suffix).
Some are Classical Latin common nouns in the nominative plural, meaning for instance ‘the plants’, ‘the seaweeds’, ‘the mosses’.
Article 18.5[2] of the ICN allows a descriptive name, of long usage, for the following eight families.