Ligrone, Roberto, Jeffrey G. Duckett, and Karen S. Renzaglia. “Major transitions in the evolution of early land plants: a bryological perspective.” Annals of botany 109, no. 5 (2012): 851-871.
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Molecular phylogeny has resolved the liverworts as the earliest-divergent clade of land plants and mosses as the sister group to hornworts plus tracheophytes, with alternative topologies resolving the hornworts as sister to mosses plus tracheophytes less well supported. The tracheophytes plus fossil plants putatively lacking lignified vascular tissue form the polysporangiophyte clade.