The eudicots or eudicotyledons are

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

s that have two seed leaves (cotyledons) upon

germination Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, ...

. The term derives from ''

dicotyledon The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two groups into which all the flowering plants (angiosperms) were formerly divided. The name refers to one of the typical characteristics of the group: namely, ...

'' (etymologically, ''eu'' = true; ''di'' = two; ''cotyledon'' = seed leaf). Historically, authors have used the terms tricolpates or non-magnoliid dicots. The current botanical terms were introduced in 1991, by evolutionary botanist James A. Doyle and paleobotanist Carol L. Hotton, to emphasize the later evolutionary

divergence In vector calculus, divergence is a vector operator that operates on a vector field, producing a scalar field giving the rate that the vector field alters the volume in an infinitesimal neighborhood of each point. (In 2D this "volume" refers to ...

of tricolpate dicots from earlier, less specialized, dicots. Scores of familiar plants are eudicots, including many commonly cultivated and edible plants, numerous

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...

s, tropicals and ornamentals. Among the most well-known eudicot genera are those of the

sunflower The common sunflower (''Helianthus annuus'') is a species of large annual forb of the daisy family Asteraceae. The common sunflower is harvested for its edible oily seeds, which are often eaten as a snack food. They are also used in the pr ...

(''

Helianthus ''Helianthus'' () is a genus comprising around 70 species of annual and perennial flowering plants in the daisy family Asteraceae commonly known as sunflowers. Except for three South American species, the species of ''Helianthus'' are native to ...

''), dandelion (''

Taraxacum ''Taraxacum'' () is a genus of flowering plants in the family Asteraceae, which consists of species commonly known as dandelions. The scientific and hobby study of the genus is known as taraxacology. The genus has a near-cosmopolitan distribu ...

''), forget-me-not ('' Myosotis''), cabbage ('' Brassica''),

apple An apple is a round, edible fruit produced by an apple tree (''Malus'' spp.). Fruit trees of the orchard or domestic apple (''Malus domestica''), the most widely grown in the genus, are agriculture, cultivated worldwide. The tree originated ...

(''

Malus ''Malus'' ( or ) is a genus of about 32–57 species of small deciduous trees or shrubs in the family Rosaceae, including the domesticated orchard apple, crab apples (sometimes known in North America as crabapples) and wild apples. The genus i ...

''), buttercup ('' Ranunculus''),

maple ''Acer'' is a genus of trees and shrubs commonly known as maples. The genus is placed in the soapberry family Sapindaceae.Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 nd more or less continuously updated si ...

('' Acer'') and macadamia (''Macadamia''). Most leafy, mid-latitude trees are also classified as eudicots, with notable exceptions being the magnolias and American tulip tree (''

Liriodendron ''Liriodendron'' () is a genus of two species of characteristically large trees, deciduous tree, deciduous over most of their populations, in the magnolia family (biology), family (Magnoliaceae). These trees are widely known by the common name ...

'')—which belong to the magnoliids—and '' Ginkgo biloba'', which is not an angiosperm.

Description

The close relationships among flowering plants with tricolpate pollen grains was initially seen in morphological studies of shared derived characters. These plants have a distinct trait in their pollen grains of exhibiting three colpi or grooves paralleling the polar axis. Later molecular evidence confirmed the genetic basis for the evolutionary relationships among flowering plants with tricolpate pollen grains and dicotyledonous traits. The term means "true dicotyledons", as it contains the majority of plants that have been considered dicots and have characteristics of the dicots. One of the genetic traits which defines the eudicots is the duplication of DELLA protein-encoding genes in their most recent common ancestor. The term "eudicots" has subsequently been widely adopted in

botany Botany, also called plant science, is the branch of natural science and biology studying plants, especially Plant anatomy, their anatomy, Plant taxonomy, taxonomy, and Plant ecology, ecology. A botanist or plant scientist is a scientist who s ...

to refer to one of the two largest clades of

angiosperm Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed within a fruit ...

s (constituting over 70% of the angiosperm species), monocots being the other. The remaining angiosperms include magnoliids and what are sometimes referred to as

basal angiosperms The basal angiosperms are the flowering plants which diverged from the lineage leading to most flowering plants. In particular, the most basal angiosperms were called the ANITA grade, which is made up of ''Amborella'' (a single species of shrub f ...

or paleodicots, but these terms have not been widely or consistently adopted, as they do not refer to a

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

group. According to molecular clock calculations, the lineage that led to eudicots split from other plants about 134

million years ago Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to (i.e. years), or approximately 31.6 teraseconds. Usage Myr is in common use in fields such as Earth science and cosmology. Myr is also used w ...

or 155–160 million years ago. Fossil records suggested that basal eudicots were already diverse around 121 million years ago .

Taxonomy

The earlier name for the eudicots is tricolpates, a name which refers to the grooved structure of the

pollen Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced Gametophyte#Heterospory, microgametophytes), which produce male gametes (sperm ...

. Members of the group have tricolpate pollen, or forms derived from it. These pollens have three or more pores set in furrows called colpi. In contrast, most of the other seed plants (that is the

gymnosperms The gymnosperms ( ; ) are a group of woody, perennial Seed plant, seed-producing plants, typically lacking the protective outer covering which surrounds the seeds in flowering plants, that include Pinophyta, conifers, cycads, Ginkgo, and gnetoph ...

, the monocots and the paleodicots) produce monosulcate pollen, with a single pore set in a differently oriented groove called the sulcus. The name "tricolpates" is preferred by some botanists to avoid confusion with the dicots, a nonmonophyletic group. The name "eudicots" (plural) is used in the APG systems (from

APG system The APG system (Angiosperm Phylogeny Group system) of plant classification is the first version of a modern, mostly molecular-based, system of plant taxonomy. Published in 1998 by the Angiosperm Phylogeny Group, it was replaced by the improved ...

, of 1998, to APG IV system, of 2016) for classification of angiosperms. It is applied to a

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

, a monophyletic group, which includes most of the (former) dicots. "Tricolpate" is a synonym for the " Eudicot"

group, the "true dicotyledons" (which are distinguished from all other flowering plants by their tricolpate

structure). The number of pollen grain ''furrows'' or ''pores'' helps classify the

s, with eudicots having three colpi (tricolpate), and other groups having one sulcus. Pollen apertures are any modification of the wall of the pollen grain. These modifications include thinning, ridges and pores, they serve as an exit for the pollen contents and allow shrinking and swelling of the grain caused by changes in moisture content. The elongated apertures/ furrows in the pollen grain are called ''colpi'' (singular ''colpus''), which, along with pores, are a chief criterion for identifying the pollen classes.

Subdivisions

The eudicots can be divided into two groups: the basal eudicots and the core eudicots. Basal eudicot is an informal name for a

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

group. The core eudicots are a monophyletic group. A 2010 study suggested the core eudicots can be divided into two clades, Gunnerales and a clade called Pentapetalae, comprising all the remaining core eudicots. The Pentapetalae can be then divided into three clades: * Dilleniales * superrosids consisting of

Saxifragales Saxifragales is an order (biology), order of flowering plants in the Superrosids, superrosid clade of the eudicots. It contains 15 Families (biology), families and around 100 genera, with nearly 2,500 species. Well-known and economically import ...

and rosids (the APG IV system includes the Vitales in the rosids) * superasterids consisting of Santalales, Berberidopsidales, Caryophyllales and

asterids Asterids are a large clade (monophyly, monophyletic group) of flowering plants, composed of 17 Order_(biology), orders and more than 80,000 species, about a third of the total flowering plant species. The asterids are divided into the unranked cl ...

This division of the eudicots is shown in the following cladogram:Based on:

---- The following is a more detailed breakdown according to APG IV, showing within each clade and orders: * clade Eudicots *: order

Ranunculales Ranunculales is an order of flowering plants. Of necessity it contains the family Ranunculaceae, the buttercup family, because the name of the order is based on the name of a genus in that family. Ranunculales belongs to a paraphyletic group k ...

*: order Proteales *: order Trochodendrales *: order Buxales *: clade Core eudicots *:: order Gunnerales *:: order Dilleniales *:: clade Superrosids *::: order

*::: clade Rosids *:::: order Vitales *:::: clade Fabids *::::: order Fabales *::::: order Rosales *::::: order Fagales *::::: order

Cucurbitales The Cucurbitales are an order of flowering plants, included in the rosid group of dicotyledons. This order mostly belongs to tropical areas, with limited presence in subtropical and temperate regions. The order includes shrubs and trees, togeth ...

*::::: order Oxalidales *::::: order Malpighiales *::::: order Celastrales *::::: order Zygophyllales *:::: clade Malvids *::::: order Geraniales *::::: order Myrtales *::::: order Crossosomatales *::::: order Picramniales *::::: order

Malvales The Malvales are an Order (biology), order of flowering plants. As circumscribed by Angiosperm Phylogeny Group, APG II-system, the order includes about 6000 species within nine Family (biology), families. The order is placed in the eurosids II, w ...

*::::: order

Brassicales The Brassicales (or Cruciales) are an order (biology), order of flowering plants, belonging to the malvid group of eudicotyledons under the APG IV system. Well-known members of Brassicales include cabbage, cauliflower, Brussels sprout, broccoli, ...

*::::: order Huerteales *::::: order Sapindales *:: clade Superasterids *::: order Berberidopsidales *::: order Santalales *::: order Caryophyllales *::: clade

Asterids Asterids are a large clade (monophyly, monophyletic group) of flowering plants, composed of 17 Order_(biology), orders and more than 80,000 species, about a third of the total flowering plant species. The asterids are divided into the unranked cl ...

*:::: order Cornales *:::: order Ericales *:::: clade

Campanulids Asterids are a large clade (monophyly, monophyletic group) of flowering plants, composed of 17 Order_(biology), orders and more than 80,000 species, about a third of the total flowering plant species. The asterids are divided into the unranked cl ...

*::::: order Aquifoliales *::::: order

Asterales Asterales ( ) is an Order (biology), order of dicotyledonous flowering plants that includes the large Family (biology), family Asteraceae (or Compositae) known for composite flowers made of Floret#floret, florets, and ten families related to th ...

*::::: order Escalloniales *::::: order Bruniales *::::: order Apiales *::::: order Dipsacales *::::: order Paracryphiales *:::: clade Lamiids *::::: order Solanales *::::: order Lamiales *::::: order Vahliales *::::: order Gentianales *::::: order Boraginales *::::: order Garryales *::::: order Metteniusales *::::: order Icacinales

References

Bibliography

* *
Eudicots
in Stevens, P. F. (2001 onwards)
Angiosperm Phylogeny Website
Version 7, May 2006.

External links

* *
Eudicots
', Tree of Life Web Project * Plant Life Forms {{Taxonbar, from=Q165468 Plant unranked clades Early Cretaceous plants Extant Early Cretaceous first appearances