The rosids are members of a large clade ( monophyletic group) of

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, containing about 70,000

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 ...

, more than a quarter of all

angiosperms 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 ...

. The clade is divided into 16 to 20 orders, depending upon

circumscription Circumscription may refer to: *Circumscribed circle * Circumscription (logic) *Circumscription (taxonomy) *Circumscription theory, a theory about the origins of the political state in the history of human evolution proposed by the American anthrop ...

and classification. These orders, in turn, together comprise about 140

families Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Ideal ...

. Fossil rosids are known from 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 ...

period.

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 nucleo ...

estimates indicate that the rosids originated in the Aptian or

Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/ Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± 0 ...

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 Under the International Code of Nomenclature for algae, fungi, and plants (ICN), Rosidae is a botanical name at the rank of subclass. Circumscription of the subclass will vary with the taxonomic system being used; the only requirement being t ...

", which had usually been understood to be a subclass. In 1967, Armen Takhtajan showed that the correct basis for the name "Rosidae" is a description of a

group A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic ide ...

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 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, order, class, phylum, kingdom, domain. While ...

like the names authorized by the

ICBN The ''International Code of Nomenclature for algae, fungi, and plants'' (ICN) is the set of rules and recommendations dealing with the formal botanical names that are given to plants, fungi and a few other groups of organisms, all those "trad ...

. The rosids are monophyletic based upon evidence found by molecular phylogenetic analysis. Three different

definitions 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 definiti ...

of the rosids were used. Some authors included the orders

Saxifragales The Saxifragales (saxifrages) are an order of flowering plants (Angiosperms). They are an extremely diverse group of plants which include trees, shrubs, perennial herbs, succulent and aquatic plants. The degree of diversity in terms of vegeta ...

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 ...

in the rosids. Others excluded both of these orders. The circumscription used in this article is that of the

APG IV The APG IV system of flowering plant classification is the fourth version of a modern, mostly molecular-based, system of plant taxonomy for flowering plants (angiosperms) being developed by the Angiosperm Phylogeny Group (APG). It was publishe ...

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 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 dicots ...

minus

Gunnerales The Gunnerales are an order of flowering plants. In the APG III system (2009) and APG IV system (2016) it contains two genera: '' Gunnera'' (in family Gunneraceae) and ''Myrothamnus'' (in family Myrothamnaceae). In the Cronquist system (1981), ...

), the others being

Dilleniales The Dilleniales are an order of flowering plants, potentially containing one family, Dilleniaceae. The APG III system of 2009, like the earlier APG II system of 2003, left the Dilleniaceae unplaced as to order, while noting that the name Dillenia ...

and the superasterids (

Berberidopsidales Berberidopsidales is an order of Southern Hemisphere woody flowering plants. The name is newly accepted in the APG III system of plant taxonomy. APG II system, of 2003, mentions the possibility of recognizing the order, as comprising the familie ...

Caryophyllales Caryophyllales ( ) is a diverse and heterogeneous order of flowering plants that includes the cacti, carnations, amaranths, ice plants, beets, and many carnivorous plants. Many members are succulent, having fleshy stems or leaves. The betalai ...

Santalales The Santalales are an order of flowering plants with a cosmopolitan distribution, but heavily concentrated in tropical and subtropical regions. It derives its name from its type genus ''Santalum'' (sandalwood). Mistletoe is the common name for a ...

, and

asterids In the APG IV system (2016) for the classification of flowering plants, the name asterids denotes a clade (a monophyletic group). Asterids is the largest group of flowering plants, with more than 80,000 species, about a third of the total flowe ...

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 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 spe ...

of rosids shown below is adapted from the

Angiosperm Phylogeny Group The Angiosperm Phylogeny Group (APG) is an informal international group of systematic botanists who collaborate to establish a consensus on the taxonomy of flowering plants (angiosperms) that reflects new knowledge about plant relationships disc ...

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 Actinor ...

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 air is converted into ammonia () or related nitrogenous compounds, typically in soil or aquatic systems but also in industry. Atmo ...

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