Книга: Pteridophyte: Pteridophyte, Vascular Plant, Xylem, Phloem, Seed, Lycopodiophyta, Clade, Equisetopsida, Psilotopsida, Ophioglossales

High Quality Content by WIKIPEDIA articles! The pteridophytes are vascular plants (plants with xylem and phloem) that neither flower nor produce seeds, hence they are called vascular cryptogams. Instead, they reproduce and disperse only via spores. These plants are generally sporophyte-oriented that is, the normal plant is the diploid sporophyte, with the only haploid structure being the gametophyte (prothallium) in season. This basic pattern is like that found in the seed plants but with an important exception. Unlike the seed plants, the pteridophytes have a gametophyte stage that is free-living. As a result, pteridophyte sexuality is more complicated than that of the seed plants.