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a large group of higher plants to which are sometimes assigned all higher seedless plants except mosses (Bryophyta). Unlike the bryophytes, the sporophyte—the asexual generation—is well developed and divided, except in Psilotophyta, into stems, leaves, and roots. Spores develop, from which emerges the gametophyte—the sexual generation. The gametophyte is poorly developed, almost undifferentiated, and bears sexual organs (in males, antheridia, and in females, archegonia). After fertilization, another asexual generation develops.
The Pteridophyta include ferns, horsetails, clubmosses, selaginellas, isoetes, psilotaceous plants, and many extinct groups of plants. They were formerly regarded as a single taxonomic group —a division (or subdivision)—and were divided into a number of classes. On the basis of an extensive study of the vegetative and reproductive organs of extinct and extant plants, the group Pteridophyta has been divided into several natural divisions, each of which has its own history. These include the Psilotophyta, Lycopodiophyta, Equisetineae, and Polypodiophyta.