Mesangiospermae (core angiosperms) is a

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

s (angiosperms), informally called "mesangiosperms". They are one of two main groups of angiosperms. It is a name created under the rules of the '' PhyloCode'' system of

phylogenetic nomenclature Phylogenetic nomenclature is a method of nomenclature for taxa in biology that uses phylogenetic definitions for taxon names as explained below. This contrasts with the traditional approach, in which taxon names are defined by a '' type'', which ...

. There are about 350,000

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of mesangiosperms.Alan J. Paton, Neil Brummitt,

Rafaël Govaerts Rafaël Herman Anna Govaerts (born 1968) is a Belgian botanist. He is particularly noted for his work on plant taxonomy. He has worked at the Royal Botanic Gardens, Kew since the 1990s, and is the principal contributor to the World Checklist of ...

, 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. The mesangiosperms contain about 99.95% of the flowering plants, assuming that there are about 175 species not in this group

Peter F. Stevens Peter Francis Stevens is a British botanist born in 1944. He is a researcher at the Missouri Botanical Garden and professor of Biology of the University of Missouri–St. Louis. He is a member of the Angiosperm Phylogeny Group which created t ...

(2001 onwards). Angiosperm Phylogeny Website In: Missouri Botanical Garden Website. (see ''External links'' below). and about 350,000 that are. While such a clade with a similar circumscription exists in the

APG III system The APG III system of flowering plant classification is the third version of a modern, mostly molecular-based, system of plant taxonomy being developed by the Angiosperm Phylogeny Group (APG). Published in 2009, it was superseded in 2016 by a fur ...

, it was not given a name.

Phylogeny

Besides the mesangiosperms, the other groups of flowering plants are Amborellales,

Nymphaeales The Nymphaeales are an order (biology), order of flowering plants, consisting of three Family (biology), families of aquatic plants, the Hydatellaceae, the Cabombaceae, and the Nymphaeaceae (water lilies). It is one of the three orders of basal a ...

, and Austrobaileyales. These constitute a

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

grade called basal angiosperms. The

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

names A name is a term used for identification by an external observer. They can identify a class or category of things, or a single thing, either uniquely, or within a given context. The entity identified by a name is called its referent. A persona ...

, ending in -ales are used here without reference to taxonomic rank because these groups contain only one order. Mesangiospermae includes the following clades: * Ceratophyllales *

Chloranthales Chloranthaceae is a family of flowering plants (angiosperms), the only family in the order Chloranthales. It is not closely related to any other family of flowering plants, and is among the early-diverging lineages in the angiosperms. They are ...

eudicots The eudicots, Eudicotidae, or eudicotyledons are a clade of flowering plants mainly characterized by having two seed leaves upon germination. The term derives from Dicotyledons. Traditionally they were called tricolpates or non-magnoliid dico ...

* magnoliidae * monocots

Name

The mesangiosperms are usually recognized in

classification Classification is a process related to categorization, the process in which ideas and objects are recognized, differentiated and understood. Classification is the grouping of related facts into classes. It may also refer to: Business, organizat ...

systems A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and express ...

that do not assign groups to

taxonomic rank In biological classification, taxonomic rank is the relative level of a group of organisms (a taxon) in an ancestral or hereditary hierarchy. A common system consists of species, genus, family (biology), family, order (biology), order, class (b ...

. The name Mesangiospermae is a branch-modified node-based name in

. It is

defined A definition is a statement of the meaning of a term (a word, phrase, or other set of symbols). Definitions can be classified into two large categories: intensional definitions (which try to give the sense of a term), and extensional defini ...

as the most inclusive crown clade containing '' Platanus occidentalis'', but not ''

Amborella trichopoda ''Amborella'' is a monotypic genus of understory shrubs or small trees endemic to the main island, Grande Terre, of New Caledonia in the southwest Pacific Ocean. The genus is the only member of the family Amborellaceae and the order Amborellale ...

'', ''

Nymphaea odorata ''Nymphaea odorata'', also known as the American white waterlily, fragrant water-lily, beaver root, fragrant white water lily, white water lily, sweet-scented white water lily, and sweet-scented water lily, is an aquatic plant belonging to the ge ...

'', or '' Austrobaileya scandens''.Philip D. Cantino, James A. Doyle, Sean W. Graham,

Walter S. Judd Walter S. Judd (born 1951) is an American botanist and taxonomist, and distinguished professor in the Department of Botany, University of Florida since 2009. Career Judd attended Michigan State University (B.S. 1973, M.S. 1974) and Harvard Univ ...

, Richard G. Olmstead,

Douglas E. Soltis Douglas Soltis is a Distinguished Professor in the Laboratory of Molecular Systematics & Evolutionary Genetics, (Soltis lab.) Florida Museum of Natural History and Department of Biology at the University of Florida. His research interests are in ...

Pamela S. Soltis Pamela Soltis (born November 13, 1957) is an American botanist. She is a distinguished professor at the University of Florida, curator at the Florida Museum of Natural History, principal investigator of the Laboratory of Molecular Systematics an ...

, 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). 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.

Description

molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

studies Study or studies may refer to: General * Education **Higher education * Clinical trial * Experiment * Observational study * Research * Study skills, abilities and approaches applied to learning Other * Study (art), a drawing or series of drawin ...

, the mesangiosperms are always strongly supported as a

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

group.

, Peter K. Endress, and

Mark W. Chase Mark Wayne Chase (born 1951) is a US-born British botanist. He is noted for work in plant classification and evolution, and one of the instigators of the Angiosperm Phylogeny Group-classification for flowering plants which is partly based on DNA ...

(2005). ''Phylogeny and Evolution of the Angiosperms''. Sinauer: Sunderland, MA 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.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. The

ovule In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the megasporangium), and the fe ...

contains a

megagametophyte A gametophyte () is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the ...

, also known as an

embryo sac In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the megasporangium), and the fe ...

, that is

bipolar Bipolar may refer to: Astronomy * Bipolar nebula, a distinctive nebular formation * Bipolar outflow, two continuous flows of gas from the poles of a star Mathematics * Bipolar coordinates, a two-dimensional orthogonal coordinate system * Bipolar ...

in structure and contains 8 cell nuclei. The

antipodal cell In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the megasporangium), and the fe ...

s are

persistent Persistent may refer to: * Persistent data * Persistent data structure * Persistent identifier * Persistent memory * Persistent organic pollutant * Persistent Systems, a technology company * USS ''Persistent'', three United States Navy ships See ...

, and the

endosperm The endosperm is a tissue produced inside the seeds of most of the flowering plants following double fertilization. It is triploid (meaning three chromosome sets per nucleus) in most species, which may be auxin-driven. It surrounds the embryo and ...

is triploid.

History

The oldest known

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s of flowering plants are fossil mesangiosperms from the

Hauterivian The Hauterivian is, in the geologic timescale, an age in the Early Cretaceous Epoch or a stage in the Lower Cretaceous Series. It spans the time between 132.9 ± 2 Ma and 129.4 ± 1.5 Ma (million years ago). The Hauterivian is preceded by the Va ...

stage of the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

period.

Else Marie Friis Else Marie Friis (born 18 June 1947) is a Danish botanist and paleontologist. She is Professor Emerita in the Department of Geoscience at Aarhus University. Her work has been fundamental in the phylogenetic analysis of angiosperms, with widespre ...

, 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.

Molecular clock The molecular clock is a figurative term for a technique that uses the mutation rate of biomolecules to deduce the time in prehistory when two or more life forms diverged. The biomolecular data used for such calculations are usually nucleoti ...

comparisons of DNA sequences indicate that the mesangiosperms originated between 140 and 150

Mya Mya may refer to: Brands and product names * Mya (program), an intelligent personal assistant created by Motorola * Mya (TV channel), an Italian Television channel * Midwest Young Artists, a comprehensive youth music program Codes * Burmese ...

(million years ago) near the beginning of the Cretaceous period.T. Jonathan Davies, Timothy G. Barraclough,

, 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. This was about 25 Ma (million years) after the origin of the angiosperms in the mid-

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...

.Michael J. Moore, Charles D. Bell,

, and

(2007). "Using plastid genome-scale data to resolve enigmatic relationships among basal angiosperms". ''Proceedings of the National Academy of Sciences'' 104(49):19363-19368. By 135Mya, the mesangiosperms had radiated into 5 groups:

Magnoliids Magnoliids (or Magnoliidae or Magnolianae) are a clade of flowering plants. With more than 10,000 species, including magnolias, nutmeg, bay laurel, cinnamon, avocado, black pepper, tulip tree and many others, it is the third-largest group of angio ...

, Monocots, Ceratophyllales, and

Eudicots The eudicots, Eudicotidae, or eudicotyledons are a clade of flowering plants mainly characterized by having two seed leaves upon germination. The term derives from Dicotyledons. Traditionally they were called tricolpates or non-magnoliid dico ...

. 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 tree A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...

s. In 2007, two studies attempted to

resolve Resolve may refer to: * ''Resolve'' (Lagwagon album) * ''Resolve'' (Last Tuesday album) * "Resolve" (song), by the Foo Fighters *'' The Resolve'', a 1915 American silent short drama film * "Resolve" (''One Tree Hill'' episode) *''Resolve'', a Brit ...

the

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

relationships among these 5 groups by comparing large portions of their

chloroplast A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in ...

genomes In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding gen ...

.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 These studies agreed on the most likely phylogeny for the mesangiosperms. In this phylogeny, the monocots are sister to the clade eratophyllales + eudicots However, this result is not strongly supported. The approximately unbiased topology

test Test(s), testing, or TEST may refer to: * Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities Arts and entertainment * ''Test'' (2013 film), an American film * ''Test'' (2014 film), ...

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. This was unavoidable, because complete chloroplast genome sequences are known for only a few plants.

References

Bibliography

* * *

External links

Angiosperm Phylogeny
a
Missouri Botanical Garden

Electronic Supplement to Cantino et alii

Divergence Times
T. Jonathan Davies et alii. (2004). ''PNAS'' 101(7):1904-1909.

In
Montreal genomics
{{Taxonbar, from=Q2710933 Angiosperms Plant unranked clades