WordNet (r) 3.0 (2006):

division Bryophyta
    n 1: a division of nonflowering plants characterized by rhizoids
         rather than true roots and having little or no organized
         vascular tissue and showing alternation of generations
         between gamete-bearing forms and spore-bearing forms;
         comprises true mosses (Bryopsida) and liverworts
         (Hepaticopsida) and hornworts (Anthoceropsida) [syn:
         Bryophyta, division Bryophyta]