17.1. The name of an order or suborder is taken either from distinctive characters of the taxon (descriptive name) or from a legitimate name of an included family based on a generic name (automatically typified name). An ordinal name of the second category is formed by replacing the termination -aceae by -ales . A subordinal name of the second category is similarly formed, with the termination -ineae.
Ex. 1. Descriptive names of orders: Centrospermae, Parietales, Farinosae; of a suborder: Enantioblastae.
Ex. 2. Automatically typified names: Fucales, Polygonales, Ustilaginales; Bromeliineae, Malvineae.
17.2. Names intended as names of orders, but published with their rank denoted by a term such as "cohors", "nixus", "alliance", or "Reihe" instead of "order", are treated as having been published as names of orders.
17.3. When the name of an order or suborder based on a
name of a genus has been published with an improper Latin termination,
this termination must be changed to accord with the rule, without
change of the author's name or date of publication.
17A.1. Authors should not publish new names of orders for
taxa of that rank which include a family from whose name an existing
ordinal name is derived.