order Sphagnales or·dersp·hag·nales uncommon noun 1. coextensive with the genus Sphagnum; in some classifications isolated in a separate subclass SynonymsSphagnalesorder Sphagnales Related words Broader terms plant order Parts Bryopsida Part of genus Sphagnum WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.