The relationships among the major groups of vascular plants have become clearer in recent years. Investigations into the origin and evolution of the major groups of vascular plants indicate that there is a deep division of the vascular plants into two lineages. One of these lineages includes only the lycophytes (clubmosses, spikemosses, and quillworts), accounting for less than 1% of vascular plant species. The other lineage (known as Euphyllophyta) includes two major clades: the spermatophytes or seed plants (including more than 250,000 species of angiosperms [flowering plants], conifers, cycads, gnetophytes, and the Gingko) and the monilophytes or ferns (sensu lato, including the horsetails, whisk ferns, and eusporangiate and leptosporangiate ferns, with most of the roughly 12,000 monilophyte species being leptosporangiate ferns).
(Pryer et al. 2001; Pryer et al. 2004; Smith et al. 2006; Lehtonen 2011 and references therein)
- Lehtonen S. 2011. Towards Resolving the Complete Fern Tree of Life. PLoS ONE 6(10): e24851. doi:10.1371/journal.pone.0024851
- Pryer, K.M., H. Schneider H, A.R. Smith, et al. 2001. Horsetails and ferns are a monophyletic group and the closest living relatives to seed plants. Nature 409: 618–622.
- Pryer, K.M., E. Schuettpelz, P.G. Wolf, et al. 2004. Phylogeny and evolution of ferns (monilophytes) with a focus on the early leptosporangiate divergences. American Journal of Botany 91(10): 1582-1598.
- Smith, A.R., K.M. Pryer, E. Schuettpelz, et al. 2006. A classification of extant ferns. Taxon 55(3): 705-731.