Progressing distally from the root, Psilophyton crenulatum, the most basal clade, comprises the psilotophytes Psilotum + Tmesipteris, followed by the equisetophyte Equisetum, the seed plant Pinus, the ophioglossalean ferns Ophioglossum + Botrychium, the marattiaceous ferns Marattia + Angiopteris, and the "leptosporangiate" clade that consists of the Filicales + the Hydropteridales [ILLUSTRATION FOR FIGURE 4 OMITTED].
Kenrick and Crane (1997: [ILLUSTRATION FOR FIGURE 4:31 OMITTED]) recognize as the "Euphyllophytina" a clade that includes Devonian representatives of trimerophytes, equisetophytes, fernlike plants, and progymnosperms, and their analysis identifies six synapomorphies that define this clade [ILLUSTRATION FOR FIGURE 1 OMITTED].
The current study includes 52 taxa that represent all of the major groups of ferns and fernlike plants (Rothwell, 1996a), as well as representatives of lignophytes, equisetophytes, and other putatively related groups that make up the Euphyllophytina (Kenrick & Crane, 1997; Appendix 1).
Progressing distally, these clades are: the stauropterid ferns (Fern Clade #1); the trimerophyte Psilophyton crenulatum; the living psilotophytes Psilotum + Tmesipteris; a clade consisting of the lignophytes + (equisetophytes + Paleozoic ferns of the Cladoxylales and Zygopteridales) (Fern Clade #2); and a clade that includes all of the fern groups with living species (Fern Clade #3).
A single character state changes on the branch subtending Fern Clade #2, sister group to the equisetophytes [ILLUSTRATION FOR FIGURE 3 OMITTED]: #36, peripheral loops absent [right arrow] present.
Cladoxylalean ferns plus Zygopteridalean ferns (including Rhacophyton; Fern Clade #2 in [ILLUSTRATION FOR FIGURE 2 OMITTED]) form a clade that is related more closely to equisetophytes and lignophytes than to other groups of fernlike plants.