Psilotophyta (the "whisk ferns"; also sometimes as Psilophyta) is a division (i.e., phylum) of the Kingdom Plantae. This division contains only two genera, Psilotum, a small shrubby plant of the dry tropics, and Tmesipteris, an epiphyte found in Australia, New Zealand, and New Caledonia. There has long been controversy about the relationships of the Psilotophyta, with some claiming that they are ferns (Pteridophyta), and others maintaining that they are descendants of the first vascular plants. Recent evidence from DNA suggests a closer affinity to the ferns. This article discusses categorisations of organisms. ... In biology, a kingdom or regnum is the top-level, or nearly the top-level, taxon of organisms in scientific classification. ... Divisions Green algae land plants (embryophytes) non-vascular embryophytes Hepatophyta - liverworts Anthocerophyta - hornworts Bryophyta - mosses vascular plants (tracheophytes) seedless vascular plants Lycopodiophyta - clubmosses Equisetophyta - horsetails Pteridophyta - true ferns Psilotophyta - whisk ferns Ophioglossophyta - adderstongue ferns seed plants (spermatophytes) †Pteridospermatophyta - seed ferns Pinophyta - conifers Cycadophyta - cycads Ginkgophyta - ginkgo Gnetophyta - gnetae Magnoliophyta - flowering... An example of an epiphyte assemblage of orchids and bromeliads in a garden setting The term epiphyte refers to any plant that grows upon or attached to another living plant. ... Classes Marattiopsida Osmundopsida Gleicheniopsida Pteridopsida A fern, or pteridophyte, is any one of a group of some twenty thousand species of plants classified in the Division Pteridophyta, formerly known as Filicophyta. ... Space-filling model of a section of DNA molecule Deoxyribonucleic acid (DNA) or deoxyribose nucleic acid is a nucleic acid that contains the genetic instructions specifying the biological development of all cellular forms of life (and many viruses). ...

All Psilotophyta share a few characteristics. Psilotophyta are vascular plants. They lack leaves, instead having small outgrowths called enations. The enations are not considered true leaves because there is only a vascular bundle just underneath them, but not inside, as in leaves. Psilotophyta also do not have true roots. They are anchored by rhizoids. Absorption is aided by symbiotic fungi called mycorrhizae. Divisions Non-seed-bearing plants Equisetophyta Lycopodiophyta Psilotophyta Pteridophyta Superdivision Spermatophyta Pinophyta Cycadophyta Ginkgophyta Gnetophyta Magnoliophyta The vascular plants are those plants that have specialized cells for conducting water and sap within their tissues, including the ferns, clubmosses, horsetails, flowering plants, conifers and other gymnosperms, but not mosses, algae, and... In vascular plants, the root is that organ of a plant body that typically lies below the surface of the soil (compare with stem). ... Rhizoids, in fungi, are small branching hyphae that grow downwards from the stolons that anchors the fungus; they release digestive enzymes, and absorbs digested organic material. ... Divisions Microsporidia Chytridiomycota Zygomycota Ascomycota Basidiomycota Yellow fungus For the fictional character, see Fungus the Bogeyman. ... A mycorrhiza (typically seen in the plural form mycorrhizae meaning fungus roots) is a distinct type of root symbiosis in which individual hyphae extending from the mycelium of a fungus colonize the roots of a host plant. ...

Three sporangia are united into a synangium, which is considered to be a very reduced series of branches. There is a thick tapetum to nourish the developing spores, as is typical of eusporangiate plants. The gametophyte looks like a small piece of subterranean stem, but produces antheridia and archegonia. A sporangium (pl. ... The term spore has several different meanings in biology. ... A gametophyte is the haploid structure or phase of life of a sexually reproducing plant. ... Antheridium (plural: antheridia) is a structure or organ of the gametophyte phase of certain plants producing and containing the sperm or male gametes. ... An archegonium (pl: archegonia) (from the Greek arche = beginning and gonos = born) is a multicellular structure or organ of the gametophyte phase of certain plants producing and containing the ovum or female gamete. ...

External links

• Introduction to the Psilotales (http://www.ucmp.berkeley.edu/plants/pterophyta/psilotales.html)