Historically both lycophytes and monilophytes were grouped together as pteridophytes (ferns and fern allies) on the basis of being spore-bearing ("seed-free"). Where the monilophytes comprise about 9,000 species, including horsetails ( Equisetaceae), whisk ferns (Psilotaceae), and all eusporangiate and all leptosporangiate ferns. Infradivision Spermatophyta - seed plants, ~260,000 species.Infradivision Moniliformopses ( monilophytes).Sub division Euphyllophytina (euphyllophytes).Subdivision Lycopodiophyta (lycophytes) - less than 1% of extant vascular plants.Division Tracheophyta (tracheophytes) - vascular plants.(2006), the first higher-level pteridophyte classification published in the molecular phylogenetic era, considered the ferns as monilophytes, as follows: Of the pteridophytes, ferns account for nearly 90% of the extant diversity. Their other common characteristics include vascular plant apomorphies (e.g., vascular tissue) and land plant plesiomorphies (e.g., spore dispersal and the absence of seeds). The leaves may be microphylls or megaphylls. The stem is either underground or aerial. The body of the sporophyte is well differentiated into roots, stem and leaves. Pteridophytes (ferns and lycophytes) are free-sporing vascular plants that have a life cycle with alternating, free-living gametophyte and sporophyte phases that are independent at maturity. Ferns and lycophytes share a life cycle and are often collectively treated or studied, for example by the International Association of Pteridologists and the Pteridophyte Phylogeny Group. "Pteridophyta" is thus no longer a widely accepted taxon, but the term pteridophyte remains in common parlance, as do pteridology and pteridologist as a science and its practitioner, respectively. However, they do not form a monophyletic group because ferns (and horsetails) are more closely related to seed plants than to lycophytes.
Ferns, horsetails (often treated as ferns), and lycophytes ( clubmosses, spikemosses, and quillworts) are all pteridophytes. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as " cryptogams", meaning that their means of reproduction is hidden. Informal paraphyletic group of vascular plants that reproduce by sporesĪ pteridophyte is a vascular plant (with xylem and phloem) that disperses spores.
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