Their results arrange the Devonian species such that a clade consisting of the progymnosperm Tetraxylopteris plus the trimerophyte Pertica is the sister group to a clade that includes fernlike plants and the putative equisetophyte Hyenia (Kenrick & Crane, 1997: [ILLUSTRATION FOR FIGURE 4:31 OMITTED]).
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].
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).
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.