The rosids are members of a large

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, ...

(

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) of flowering plants, containing about 70,000 species, more than a quarter of all angiosperms. The clade is divided into 16 to 20

orders 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 ...

, depending upon circumscription and

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 ...

. These orders, in turn, together comprise about 140 families. Fossil rosids are known from the Cretaceous period. Molecular clock estimates indicate that the rosids originated in the

Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), a ...

or Albian stages of the Cretaceous, between 125 and 99.6 million years ago. Today's forests are highly dominated by rosid species, which in turn helped with diversification in many other living lineages. Additionally, rosid herbs and shrubs are also a significant part of arctic/alpine, temperate floras, aquatics, desert plants, and parasites.

Name

The name is based upon the name " Rosidae", which had usually been understood to be a subclass. In 1967,

Armen Takhtajan Armen Leonovich Takhtajan or Takhtajian ( hy, Արմեն Լևոնի Թախտաջյան; russian: Армен Леонович Тахтаджян; surname also transliterated Takhtadjan, Takhtadzhi︠a︡n or Takhtadzhian, pronounced takh-tuh-JA ...

showed that the correct basis for the name "Rosidae" is a description of a group of plants published in 1830 by

Friedrich Gottlieb Bartling Friedrich Gottlieb Bartling (December 9, 1798 – November 20, 1875) was a German botanist who was a native of Hanover. He studied natural sciences at the University of Göttingen, and in 1818 took a botanical journey through Hungary and Croatia ...

. The clade was later renamed "Rosidae" and has been variously delimited by different authors. The name "rosids" is informal and not assumed to have any particular taxonomic rank like the names authorized by the ICBN. The rosids are

based upon evidence found by

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 ...

analysis. Three different definitions of the rosids were used. Some authors included the orders Saxifragales and

Vitales The Vitaceae are a family of flowering plants, with 14 genera and around 910 known species, including common plants such as grapevines (''Vitis'' spp.) and Virginia creeper (''Parthenocissus quinquefolia''). The family name is derived from the ge ...

in the rosids. Others excluded both of these orders. The circumscription used in this article is that of the APG IV classification, which includes Vitales, but excludes Saxifragales.

Relationships

The rosids and Saxifragales form the superrosids clade. This is one of three groups that comprisee the

Pentapetalae In phylogenetic nomenclature, the Pentapetalae are a large group of eudicots that were informally referred to as the "core eudicots" in some papers on angiosperm phylogenetics.Stevens, P.F. 2006. Angiosperm Phylogeny Website, versión 7. http:/ ...

( core eudicots minus Gunnerales), the others being Dilleniales and the

superasterids The superasterids are members of a large clade (monophyletic group) of flowering plants, containing more than 122,000 species. The clade is divided into 20 orders as defined in APG IV system. These orders, in turn, together comprise about 146 fa ...

( Berberidopsidales, Caryophyllales, Santalales, and asterids).

Classification

The rosids consist of two groups: the order Vitales and the eurosids (true rosids). The eurosids, in turn, are divided into two groups: fabids (Fabidae, eurosids I) and malvids (Malvidae, eurosids II).

Orders

The rosids consist of 17 orders. In addition to Vitales, there are eight orders in fabids and eight orders in malvids. Some of the orders have only recently been recognized. These are Vitales, Zygophyllales, Crossosomatales, Picramniales, and Huerteales.

Phylogeny

The phylogeny of rosids shown below is adapted from the Angiosperm Phylogeny Group website. The ''nitrogen-fixing clade'' contains a high number of

actinorhizal plant Actinorhizal plants are a group of angiosperms characterized by their ability to form a symbiosis with the nitrogen fixing actinomycetota ''Frankia''. This association leads to the formation of nitrogen-fixing root nodules. Classification Actinorh ...

s (which have root nodules containing

nitrogen fixing Nitrogen fixation is a chemical process by which molecular nitrogen (), with a strong triple covalent bond, in the Atmosphere of Earth, air is converted into ammonia () or related nitrogenous compounds, typically in soil or aquatic systems but al ...

bacteria, helping the plant grow in poor soils). Not all plants in this clade are actinorhizal, however.

References

External links

* {{Taxonbar, from=Q338878 Extant Cretaceous first appearances Plant unranked clades