automatic taxobox taxon Polysporangiophyta authority Kenrick & Crane 1997 fossil range Latest Ordovician Recent image Aglaophyton reconstruction.jpg image caption Reconstruction of Aglaophyton , illustrating bifurcating axes with terminal sporangia, and rhizoids. image width 200px subdivision ranks Divisions subdivision Incertae sedis non vascular fossil Polysporangiophytes Horneophytopsida Aglaophyton Incertae sedis unclassified fossil Polysporangiophytes Cooksonia Salopella Tarrantia Uskiella Vascular plant s tracheophytes Rhyniopsida rhyniophytes Lycopodiophyta Lycophytina Lycopodiophyta Lycopsida clubmosses Zosterophyllophyta Zosterophyllopsida zosterophylls Euphyllophytina Eophyllophyton Trimerophytophyta Psilophyton trimerophytes Moniliformopses Cladoxylopsid a fern Filicopsida ferns Equisetopsida horsetails Radiatopses Pertica Lignophyta Spermatophyta ta seed plants Cycad atae cycads Coniferophytatae Cordaites Cordaitidra Pinophyta Coniferidra conifers Ginkgo atae ginkgo Anthophyta tae Pentoxylales Bennettitales cycadeoids Gnetae Gnetidra gnetales Flowering plant Magnolidra flowering plants Polysporangiophytes , also called polysporangiates or more formally Polysporangiophyta , are plants in which the spore bearing generation sporophyte has a structure of branching stems axes terminating in sporangium sporangia hence the name of the group which literally means many sporangia plant . The clade includes most land plants embryophyte s except for the bryophyte s liverworts, mosses and hornworts whose sporophytes are always unbranched. The definition is independent of the presence of vascular tissue . All living polysporangiophytes also have vascular tissue, i.e. are vascular plant s or tracheophytes. Fossil polysporangiophytes are known which do not have vascular tissue and so are not tracheophytes. Early polysporangiophytes History of discovery Paleobotanists distinguish between micro and megafossils. Microfossils are primarily spore s, either single or in group ... more details
For Algae disambiguation Alga disambiguation paraphyletic group domain Eukaryota image Laurencia.jpg image width 263px image caption Laurencia , a marine genus of Red Algae from Hawaii. includes Archaeplastida Chlorophyta Green algae Rhodophyta Red algae Glaucophyta Rhizaria , Excavata Chlorarachniophytes Euglenids Chromista , Alveolata Heterokonts Bacillariophyceae Diatoms Axodine Bolidomonas Eustigmatophyceae Phaeophyceae Brown algae Chrysophyceae Golden algae Raphidophyceae Synurophyceae Xanthophyceae Yellow green algae Cryptophyta Dinoflagellates Haptophyta excludes Cyanobacteria Plant ae Image AlgaeTree.png thumb 260px The lineage of algae according to Thomas Cavalier Smith . The exact number and placement of Endosymbiotic theory endosymbiotic events is currently unknown, so this diagram can be taken only as a general guide ref name keeling ref name parfrey It represents the most parsimonious way of explaining the three types of endosymbiotic origins of plastids. These types include the endosymbiotic events of cyanobacteria , red algae and green algae , leading to the hypothesis of the supergroups Archaeplastida , Chromalveolata and Cabozoa respectively. However, the monophyly of Cabozoa has been refuted and the monophylies of Archaeplastida and Chromalveolata are currently strongly challenged. Endosymbiotic events are noted by dotted lines. Algae IPAc en l d i or IPAc en l i singular alga IPAc en l , Latin language Latin for seaweed are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the Macrocystis pyrifera giant kelps that grow to 65 meters in length. They are photosynthesis photosynthetic like plant s, and simple because their tissues are not organized into the many distinct organs found in embryophyte land plants . The largest and most complex marine forms are called seaweed s. Though the Prokaryote prokaryotic cyanobacteria commonly referred to as blue gree ... more details
distinguish miosis mitosis myositis For the figure of speech meiosis figure of speech merge from Meiome date January 2012 File Meiosis Overview.svg right thumb 300px Events involving meiosis, showing chromosomal crossover Meiosis IPAc en audio en us meiosis.ogg m a o s s is a special type of cell division necessary for sexual reproduction in eukaryote s. The cells produced by meiosis are gamete s or spore s. In many organisms, including all animal s and Embryophyte land plants but not some other groups such as fungi , gametes are called sperm and Ovum egg cells . Whilst the process of meiosis bears a number of similarities with the life cycle cell division process of mitosis , it differs in two important respects the chromosomes in meiosis undergo a recombination which shuffles the genes producing a different genetic combination in each gamete, compared with the co existence of each of the two separate pairs of each chromosome one received from each parent in each cell which results from mitosis. the outcome of meiosis is four genetically unique haploid cells, compared with the two genetically identical Ploidy Diploid diploid cells produced from mitosis. Meiosis begins with one diploid cell containing two copies of each chromosome one from the organism s mother and one from its father and produces four haploid cells containing one copy of each chromosome. Each of the resulting chromosomes in the gamete cells is a unique mixture of maternal and paternal DNA, resulting in offspring that are genetically distinct from either parent. This gives rise to genetic diversity in sexually reproducing populations. This genetic diversity can provide the variation of physical and behavioural attributes phenotype s upon which natural selection can act, but, as described below in Section 6, Origin and function of meiosis, the genetic diversity may be largely a by product of the homologous recombination that is primarily employed for its DNA repair function during meiosis. It i ... more details
see also Angiosperm Phylogeny Group The APG III system Angiosperm Phylogeny Group III system of flowering plant classification is the third version of a modern, mostly Molecular phylogenetics molecular based, list of systems of plant taxonomy system of plant taxonomy . The system was published in 2009 by the Angiosperm Phylogeny Group , 6½ years after its predecessor the APG II system was published, and 11 years after the intital APG system was published in 1998. ref name apgiii Citation last Angiosperm Phylogeny Group year 2009 title An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants APG III journal Botanical Journal of the Linnean Society volume 161 issue 2 pages 105 121 url http www3.interscience.wiley.com journal 122630309 abstract accessdate 2010 12 10 doi 10.1111 j.1095 8339.2009.00996.x ref ref Citation title As easy as APG III Scientists revise the system of classifying flowering plants publisher The Linnean Society of London url http www.linnean.org index.php?id 448 accessdate 2009 10 29 date 2009 10 08 ref ref Citation title APG III tidies up plant family tree publisher Horticulture Week url http www.hortweek.com channel OrnamentalsProduction rss article 943975 APG III tidies plant family tree accessdate 2009 10 29 date 2009 10 08 ref Along with the publication outlining the new system, there were two accompanying publications in the same issue of the Botanical Journal of the Linnean Society . The first, by Chase & Reveal, was a formal phylogenetic classification of all Embryophyte land plants embryophytes , compatible with the APG III classification. As the APG have chosen to eschew ranks above order, this paper was meant to fit the system into the existing Linnaean taxonomy Linnaean hierarchy for those that prefer such a classification. The result was that all land plants were placed in the class Equisitopsida, which was then divided into 16 subclasses including the flowering plant Magnoliidae ... more details
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