{{Short description|One of two clades of flowering plants}} {{Automatic taxobox | fossil_range = | image = Flower poster 2.jpg | image_caption = ''Diversity of Mesangiosperms'' | taxon = Mesangiospermae | subdivision_ranks = Groups | subdivision = * Magnoliids * Chloranthales * Monocots * Ceratophyllales * Eudicots | synonyms= *Core angiosperms }} [[File:Liriodendron tulipifera1Foggy Bummer.jpg|thumb|Flower of ''Liriodendron tulipifera'', a Mesangiosperm]] '''Mesangiospermae''' is a clade that contains the majority of flowering plants (angiosperms). Mesangiosperms are therefore known as the '''core angiosperms''', in contrast to the three orders of earlier-diverging species known as the basal angiosperms: Nymphaeales (including water lilies), Austrobaileyales (including star anise), and Amborellales. Mesangiospermae includes about 350,000 species,<ref name="paton2008">Alan J. Paton, Neil Brummitt, Rafaël Govaerts, Kehan Harman, Sally Hinchcliffe, Bob Allkin, & Eimear Nic Lughadha (2008). "Towards Target 1 of the Global Strategy for Plant Conservation: a working list of all known plant species - progress and prospects". ''Taxon'' '''57'''(2):602-611.</ref> while there are about 175 extant species of basal angiosperms.<ref name="apweb">Peter F. Stevens (2001 onwards). Angiosperm Phylogeny Website In: Missouri Botanical Garden Website. (see ''External links'' below).</ref>
It is a name created under the rules of the ''PhyloCode'' system of phylogenetic nomenclature.<ref name="cantino2007">{{Cite journal|author=Philip D. Cantino, James A. Doyle, Sean W. Graham, Walter S. Judd, Richard G. Olmstead, Douglas E. Soltis, Pamela S. Soltis, and Michael J. Donoghue|year=2007|title=Towards a phylogenetic nomenclature of ''Tracheophyta''|journal=Taxon|volume=56|issue=3|pages=822–846|doi=10.2307/25065865|jstor=25065865}}</ref> While such a clade with a similar circumscription exists in the APG III system, it was not given a name.<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 |doi=10.1111/j.1095-8339.2009.00996.x |doi-access=free |hdl=10654/18083 |hdl-access=free }}</ref>
== Phylogeny == Besides the mesangiosperms, the other groups of flowering plants are Amborellales, Nymphaeales, and Austrobaileyales. These constitute a paraphyletic grade called basal angiosperms. The order names, ending in -ales are used here without reference to taxonomic rank because these groups contain only one order.{{clarify|date=August 2013}}
Mesangiospermae includes the following clades: * Ceratophyllales * Chloranthales * eudicots * magnoliidae * monocots
{| |{{anchor|Clad1}}'''Cladogram: The phylogenetic position of the Mesangiospermae within the angiosperms, as of APG IV (2016)'''{{sfn|APG IV|2016}} {{barlabel |size=8 |at1=2|bar1=green|label1=basal angiosperms |at2=6|bar2=purple|label2=core angiosperms |cladogram= {{clade|style=font-size:100%;line-height:100%
|label1=angiosperms |1={{cladex |1=Amborellales|barbegin1=green |2={{cladex |1=Nymphaeales|bar1=green |2={{cladex |1=Austrobaileyales|barend1=green |2={{cladex |label1='''Mesangiospermae''' |1={{cladex |1=magnoliids|barbegin1=purple |2=Chloranthales|bar2=purple |3={{cladex |1=monocots|bar1=purple |2={{cladex |1=Ceratophyllales|bar1=purple |2=eudicots|barend2=purple }} }} }} }} }} }} }} }} }} |}
==Name== The mesangiosperms are usually recognized in classification systems that do not assign groups to taxonomic rank. The name Mesangiospermae is a branch-modified node-based name in phylogenetic nomenclature. It is defined as the most inclusive crown clade containing ''Platanus occidentalis'', but not ''Amborella trichopoda'', ''Nymphaea odorata'', or ''Austrobaileya scandens''.<ref name="esuppcantino2007">Philip D. Cantino, James A. Doyle, Sean W. Graham, Walter S. Judd, Richard G. Olmstead, Douglas E. Soltis, Pamela S. Soltis, and Michael J. Donoghue. 2007. Electronic Supplement: pages E1-E44. To: Cantino et alii. 2007. "Towards a phylogenetic nomenclature of ''Tracheophyta''". ''Taxon'' '''56'''(3):822-846. (see ''External links'' below).</ref> It is sometimes written as /Mesangiospermae even though this is not required by the PhyloCode. The "clademark" slash indicates that the term is intended as phylogenetically defined.<ref name="cantino2007"/>
==Description==
In molecular phylogenetic studies, the mesangiosperms are always strongly supported as a monophyletic group.<ref name="soltis2005">Douglas E. Soltis, Pamela S. Soltis, Peter K. Endress, and Mark W. Chase (2005). ''Phylogeny and Evolution of the Angiosperms''. Sinauer: Sunderland, MA</ref> There is no distinguishing characteristic which is found in all mature mesangiosperms but which is not found in any of the basal angiosperms. Nevertheless, the mesangiosperms are recognizable in the earliest stage of embryonic development.<ref name="apweb"/><ref name="friedman2009">William E. Friedman and Kirsten C. Ryerson (2009). "Reconstructing the ancestral female gametophyte of angiosperms: Insights from Amborella and other ancient lineages of flowering plants". ''American Journal of Botany'' 96(1):129-143. {{doi|10.3732/ajb.0800311}}</ref> The ovule contains a megagametophyte, also known as an embryo sac, that is bipolar in structure and contains 8 cell nuclei. The antipodal cells are persistent, and the endosperm is triploid.
==History==
The oldest known fossils of flowering plants are fossil mesangiosperms from the Hauterivian stage of the Cretaceous period.<ref name="friis2006">Else Marie Friis, K. Raunsgaard Pedersen, and Peter R. Crane (2006). "Cretaceous angiosperm flowers: Innovation and evolution in plant reproduction". ''Palaeogeography, Palaeoclimatology, Palaeoecology''232(2-4):251–293. {{doi|10.1016/j.palaeo.2005.07.006}}</ref>
Molecular clock comparisons of DNA sequences indicate that the mesangiosperms originated between 140 and 150 Mya (million years ago) near the beginning of the Cretaceous period.<ref name="davies2004">T. Jonathan Davies, Timothy G. Barraclough, Mark W. Chase, Pamela S. Soltis, Douglas E. Soltis, and Vincent Savolainen (2004). "Darwin's abominable mystery: Insights from a supertree of the angiosperms". ''Proceedings of the National Academy of Sciences'' 101(7):1904-1909.</ref> This was about 25 Ma (million years) after the origin of the angiosperms in the mid-Jurassic.<ref name="moore2007">Michael J. Moore, Charles D. Bell, Pamela S. Soltis, and Douglas E. Soltis (2007). "Using plastid genome-scale data to resolve enigmatic relationships among basal angiosperms". ''Proceedings of the National Academy of Sciences'' 104(49):19363-19368. {{doi|10.1073/pnas.0708072104}}</ref>
By 135Mya, the mesangiosperms had radiated into 5 groups: Chloranthales, Magnoliids, Monocots, Ceratophyllales, and Eudicots.<ref name="moore2007" /> The radiation into 5 groups probably occurred in about 4 million years.
Because the interval of this radiation (about 4 million years) is short in proportion to its age (about 145 million years), it had long appeared that the 5 groups of mesangiosperms had arisen simultaneously. The mesangiosperms were shown as an unresolved pentatomy in phylogenetic trees. In 2007, two studies attempted to resolve the phylogenetic relationships among these 5 groups by comparing large portions of their chloroplast genomes.<ref name="moore2007" /><ref name=jansen2007>Robert K. Jansen, Zhengqiu Cai, Linda A. Raubeson, Henry Daniell, Claude W. dePamphilis, James Leebens-Mack, Kai F. Müller, Mary Guisinger-Bellian, Rosemarie C. Haberle, Anne K. Hansen, Timothy W. Chumley, Seung-Bum Lee, Rhiannon Peery, Joel R. McNeal, Jennifer V. Kuehl, and Jeffrey L. Boore (2007). "Analysis of 81 genes from 64 plastid genomes resolves relationships in angiosperms and identifies genome-scale evolutionary patterns" ''Proceedings of the National Academy of Sciences'' 104(49):19369-19374 {{doi|10.1073/pnas.0709121104}}</ref> These studies agreed on the most likely phylogeny for the mesangiosperms. In this phylogeny, the monocots are sister to the clade [Ceratophyllales + eudicots]. However, this result is not strongly supported. The approximately unbiased topology test showed that some of the other possible positions of the monocots had more than 5% probability of being correct. The major weakness of these 2 studies was the small number of species whose DNA was being used in the phylogenetic analysis, 45 in one study and 64 in the other.<ref name="moore2007" /> This was unavoidable, because complete chloroplast genome sequences are known for only a few plants.
== References == {{Reflist|30em}}
== Bibliography == {{refbegin}}
* {{cite journal |last = APG IV |authorlink=Angiosperm Phylogeny Group|title=An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV |year=2016 |journal=Botanical Journal of the Linnean Society |volume=181 |issue=1 |pages=1–20 |doi=10.1111/boj.12385 |doi-access=free }} * {{cite journal|last1=Soltis|first1=Pamela S|last2=Soltis|first2=Douglas E|authorlink1=Pamela Soltis|authorlink2=Douglas Soltis|title=Ancient WGD events as drivers of key innovations in angiosperms|journal=Current Opinion in Plant Biology|date=April 2016|volume=30|pages=159–165|doi=10.1016/j.pbi.2016.03.015|pmid=27064530|doi-access=free}} * {{cite journal|last1=Zeng|first1=Liping|last2=Zhang|first2=Qiang|last3=Sun|first3=Renran|last4=Kong|first4=Hongzhi|last5=Zhang|first5=Ning|last6=Ma|first6=Hong|title=Resolution of deep angiosperm phylogeny using conserved nuclear genes and estimates of early divergence times|journal=Nature Communications|date=24 September 2014|volume=5|issue=4956|pages=4956|doi=10.1038/ncomms5956|pmid=25249442|pmc=4200517|ref={{harvid|Zeng et al|2014}}|bibcode=2014NatCo...5.4956Z}} {{refend}}
== External links == * [http://www.mobot.org/MOBOT/Research/APweb/welcome.html Angiosperm Phylogeny] at [http://www.mobot.org Missouri Botanical Garden] * {{usurped|1=[https://web.archive.org/web/20080705222912/http://www.phylodiversity.net/donoghue/publications/MJD_papers/2007/165_Cantino_Taxon07.pdf Electronic Supplement to Cantino et alii]}} * [http://www.pnas.org/content/101/7/1904.full.pdf+html Divergence Times ] T. Jonathan Davies et alii. (2004). ''PNAS'' 101(7):1904-1909. * [https://web.archive.org/web/20120406161149/http://www.bch.umontreal.ca/ogmp/projects/other/cp_list.html chloroplast genome list] In: [https://web.archive.org/web/20120420015422/http://www.bch.umontreal.ca/ Montreal genomics]
{{Angiosperm orders}} {{Taxonbar|from=Q2710933}}
Category:Angiosperms Category:Plant unranked clades