Noun | 1. | Phaeophyta - coextensive with class Phaeophyceae; in some classifications subsumed in the division Heterokontophyta class Phaeophyceae, Phaeophyceae - brown algae; mostly marine and littoral eukaryotic algae class Cyclosporeae, Cyclosporeae - in more recent classifications superseded by the order Fucales division - (biology) a group of organisms forming a subdivision of a larger category |