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| image = Fern.jpg | image_width = 250px | image_caption = Fern leaf | regnum = Plantae | unranked_subregnum= Streptophyta | subregnum = Embryophyta Engler, 1892〔Engler, A. 1892. ''Syllabus der Vorlesungen über specielle und medicinisch-pharmaceutische Botanik: Eine Uebersicht über das ganze Pflanzensystem mit Berücksichtigung der Medicinal- und Nutzpflanzen.'' Berlin: Gebr. Borntraeger.〕 | subdivision_ranks = Divisions | subdivision = * Non-vascular land plants (bryophytes) * * Marchantiophyta - liverworts * * Bryophyta - mosses * * Anthocerotophyta - hornworts * * †Horneophytopsida * Vascular plants (tracheophytes) * * †Rhyniophyta—rhyniophytes * * †Zosterophyllophyta—zosterophylls * * Lycopodiophyta—clubmosses * * †Trimerophytophyta—trimerophytes * * Pteridophyta - ferns and horsetails * * Seed plants (spermatophytes) * * * †Pteridospermatophyta - seed ferns * * * Pinophyta - conifers * * * Cycadophyta - cycads * * * Ginkgophyta - ginkgo * * * Gnetophyta - gnetae * * * Magnoliophyta - flowering plants ---- Traditional groups: * Bryophyta * * Pteridophyta * * Gymnospermae * * Angiospermae | synonyms= * Cormophyta Endlicher, 1836 * Phyta Barkley, 1939〔Barkley, Fred A. ''Keys to the phyla of organisms''. Missoula, Montana. 1939.〕 * Cormobionta Rothmaler, 1948〔Rothmaler, Werner. Über das natürliche System der Organismen. ''Biologisches Zentralblatt.'' 67: 242-250. 1948.〕 * Euplanta Barkley, 1949〔Barkley, Fred A. "Un esbozo de clasificación de los organismos."'' Revista de la Facultad Nacional de Agronomia, Universidad de Antioquia, Medellín''. 10: 83-103, ().〕 * Telomobionta Takhtajan, 1964〔Takhtajan, A. (1964). The taxa of the higher plants above the rank of order. ''Taxon'' 13(5): 160-164, ().〕 * Embryobionta Cronquist et al., 1966〔Cronquist, A., Takhtajan, A. & Zimmermann, W. (1966). On the Higher Taxa of Embryobionta. Taxon, Vol. 15, No. 4 (Apr., 1966), pp. 129-134, ().〕 * Metaphyta Whittaker, 1969 * Plantae Margulis, 1971}} The Embryophyta are the most familiar subkingdom of green plants that form vegetation on earth. Living embryophytes include hornworts, liverworts, mosses, ferns, lycophytes, gymnosperms and flowering plants, and emerged from Charophyte green algae. The Embryophyta are informally called land plants because they live primarily in terrestrial habitats, while the related green algae are primarily aquatic. All are complex multicellular eukaryotes with specialized reproductive organs. The name derives from their innovative characteristic of nurturing the young embryo sporophyte during the early stages of its multicellular development within the tissues of the parent gametophyte. With very few exceptions, embryophytes obtain their energy by photosynthesis, that is by using the energy of sunlight to synthesize their food from carbon dioxide and water. ==Description== The evolutionary origins of the embryophytes are discussed further below, but they are believed to have evolved from within a group of complex green algae during the Paleozoic era (which started around ). Charales or the stoneworts may be the best living illustration of that developmental step. Embryophytes are primarily adapted for life on land, although some are secondarily aquatic. Accordingly, they are often called ''land plants'' or ''terrestrial plants''. On a microscopic level, the cells of embryophytes are broadly similar to those of green algae, but differ in that in cell division the daughter nuclei are separated by a phragmoplast. They are eukaryotic, with a cell wall composed of cellulose and plastids surrounded by two membranes. The latter include chloroplasts, which conduct photosynthesis and store food in the form of starch, and are characteristically pigmented with chlorophylls ''a'' and ''b'', generally giving them a bright green color. Embryophyte cells also generally have an enlarged central vacuole enclosed by a vacuolar membrane or tonoplast, which maintains cell turgor and keeps the plant rigid. In common with all groups of multicellular algae they have a life cycle which involves 'alternation of generations'. A multicellular generation with a single set of chromosomes – the haploid gametophyte – produces sperm and eggs which fuse and grow into a multicellular generation with twice the number of chromosomes – the diploid sporophyte. The mature sporophyte produces haploid spores which grow into a gametophyte, thus completing the cycle. Embryophytes have two features related to their reproductive cycles which distinguish them from all other plant lineages. Firstly, their gametophytes produce sperm and eggs in multicellular structures (called 'antheridia' and 'archegonia', and fertilization of the ovum takes place within the archegonium rather than in the external environment. Secondly, and most importantly, the initial stage of development of the fertilized egg (the zygote) into a diploid multicellular sporophyte, take place within the archegonium where it is both protected and provided with nutrition. This second feature is the origin of the term 'embryophyte' – the fertilized egg develops into a protected embryo, rather than dispersing as a single cell.〔 In the bryophytes the sporophyte remains dependent on the gametophyte, while in all other embryophytes the sporophyte generation is dominant and capable of independent existence. Embryophytes also differ from algae by having metamers. Metamers are repeated units of development, in which each unit derives from a single cell, but the resulting product tissue or part is largely the same for each cell. The whole organism is thus constructed from similar, repeating parts or ''metamers''. Accordingly, these plants are sometimes termed 'metaphytes' and classified as the group Metaphyta (but the Haeckel's definition of Metaphyta places some algae in this group〔http://archive.org/stream/systematischephy01haec#page/256/mode/2up〕). In all land plants a disc-like structure called a phragmoplast forms where the cell will divide, a trait only found in the land plants in the streptophyte lineage, some species within their relatives Coleochaetales, Charales and Zygnematales, as well as within subaerial species of the algae order Trentepohliales, and appears to be essential in the adaptation towards a terrestrial life style.〔(Land plants divided and ruled : Nature News )〕〔(Phragmoplastin, green algae and the evolution of cytokinesis )〕〔(Invasions of the Algae - ScienceNOW - News - Science )〕〔(All Land Plants Evolved From Single Type of Algae, Scientists Say )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Embryophyte」の詳細全文を読む スポンサード リンク
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