Definition Of Pteridophyte

A pteridophyte sensu lato is a vascular plant (with xylem and phloem) that reproduces 
via spores, and therefore was a member of the former and now invalid taxon Pteridophyta. The term is now used only informally to denote a fern (monilophyte) or lycophyte. Because pteridophytes produce neither flowers nor seeds, they are also referred to as "cryptogams". The pteridophytes include the ferns, horsetails, and the lycophytes (clubmosses, spikemosses, and quillworts). These are not a monophyletic group because ferns and horsetails are more closely related to seed plants than to the lycophytes. Therefore, "Pteridophyta" is now an invalid taxon, although the term pteridophyte remains in common parlance, as do pteridology and pteridologist as a science and its practitioner, to indicate lycophytes and ferns as an informal grouping, such as the International Association of Pteridologists and the Pteridophyte Phylogeny Group.