Eudicots

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Eudicots
Temporal range: Early Cretaceous - recent
Bladmoes kiemplanten.jpg
Two seed leaves during germination ( Brassica sp.)
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Streptophyta
Clade: Embryophytes
Clade: Polysporangiophytes
Clade: Tracheophytes
Clade: Spermatophytes
Clade: Angiosperms
Clade: Eudicots
Clades (APG IV)
Arabis pollen has three colpi. Arabis voch1-4.jpg
Arabis pollen has three colpi.

The eudicots, Eudicotidae, or eudicotyledons are a clade of flowering plants (angiosperms) which are mainly characterized by having two seed leaves (cotyledons) upon germination. [1] The term derives from dicotyledon (etymologically, eu = true; di = two; cotyledon = seed leaf). Previously, they were called tricolpates or non-magnoliid dicots by past authors. 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 of tricolpate dicots from earlier, less specialized, dicots. [2]

Contents

Scores of familiar plants are eudicots, including many commonly cultivated and edible plants, numerous trees, tropicals and ornamentals. Among the most well-known eudicot genera are those of the sunflower ( Helianthus ), dandelion ( Taraxacum ), forget-me-not ( Myosotis ), cabbage ( Brassica ), apple ( Malus ), buttercup ( Ranunculus ), maple ( 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 )—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. [3]

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. [4] The term "eudicots" has subsequently been widely adopted in botany to refer to one of the two largest clades of angiosperms (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 or paleodicots, but these terms have not been widely or consistently adopted, as they do not refer to a monophyletic group.

Taxonomy

The earlier name for the eudicots is tricolpates, a name which refers to the grooved structure of the pollen. 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 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. [5]

The name "eudicots" (plural) is used in the APG systems (from APG system, of 1998, to APG IV system, of 2016) for classification of angiosperms. It is applied to a clade, a monophyletic group, which includes most of the (former) dicots.

"Tricolpate" is a synonym for the "Eudicot" monophyletic group, the "true dicotyledons" (which are distinguished from all other flowering plants by their tricolpate pollen structure). The number of pollen grain furrows or pores helps classify the flowering plants, with eudicots having three colpi (tricolpate), and other groups having one sulcus. [6] [5]

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. [7]

Subdivisions

The eudicots can be divided into two groups: the basal eudicots and the core eudicots. [8] Basal eudicot is an informal name for a paraphyletic group. The core eudicots are a monophyletic group. [9] 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. [10]

The Pentapetalae can be then divided into three clades:

This division of the eudicots is shown in the following cladogram: [11]

eudicots
basal eudicots

(paraphyletic group: Ranunculales, Proteales, Trochodendrales, Buxales)

core eudicots

Gunnerales

Pentapetalae

Dilleniales

superrosids

Saxifragales

rosids

Vitales

eurosids

fabids (8 orders)

malvids (8 orders)

superasterids

Santalales

Berberidopsidales

Caryophyllales

asterids

Cornales

Ericales

euasterids

campanulids (7 orders)

lamiids (8 orders)

The following is a more detailed breakdown according to APG IV, showing within each clade and orders: [12]

Related Research Articles

<span class="mw-page-title-main">Malpighiales</span> Eudicot order of flowering plants

The Malpighiales comprise one of the largest orders of flowering plants, containing about 36 families and more than 16,000 species, about 7.8% of the eudicots. The order is very diverse, containing plants as different as the willow, violet, poinsettia, manchineel, rafflesia and coca plant, and are hard to recognize except with molecular phylogenetic evidence. It is not part of any of the classification systems based only on plant morphology. Molecular clock calculations estimate the origin of stem group Malpighiales at around 100 million years ago (Mya) and the origin of crown group Malpighiales at about 90 Mya.

<span class="mw-page-title-main">Magnoliales</span> Basal order of flowering plants

The Magnoliales are an order of flowering plants.

<span class="mw-page-title-main">Saxifragales</span> Order of Eudicot flowering plants in the Superrosid clade

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 vegetative and floral features makes it difficult to define common features that unify the order.

<span class="mw-page-title-main">Dicotyledon</span> Historical grouping of flowering plants

The dicotyledons, also known as dicots, 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, that the seed has two embryonic leaves or cotyledons. There are around 200,000 species within this group. The other group of flowering plants were called monocotyledons, typically each having one cotyledon. Historically, these two groups formed the two divisions of the flowering plants.

<span class="mw-page-title-main">Magnoliopsida</span>

Magnoliopsida is a valid botanical name for a class of flowering plants. By definition the class will include the family Magnoliaceae, but its circumscription can otherwise vary, being more inclusive or less inclusive depending upon the classification system being discussed.

<span class="mw-page-title-main">Ranunculales</span> Basal order of flowering plants in the eudicots

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 known as the basal eudicots. It is the most basal clade in this group; in other words, it is sister to the remaining eudicots. Widely known members include poppies, barberries, hellebores, and buttercups.

<span class="mw-page-title-main">Crossosomatales</span> Order of flowering plants

The Crossosomatales are an order, first recognized as such by APG II. They are flowering plants included within the Rosid eudicots.

<span class="mw-page-title-main">Angiosperm Phylogeny Group</span> Collaborative research group for the classification of flowering plants

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 discovered through phylogenetic studies.

<span class="mw-page-title-main">Aperture (botany)</span> Areas on the walls of a pollen grain, where the wall is thinner and/or softer

Apertures are areas on the walls of a pollen grain, where the wall is thinner and/or softer. For germination it is necessary that the pollen tube can reach out from the inside of the pollen grain and transport the sperm to the egg deep down in the pistil. The apertures are the places where the pollen tube is able to break through the pollen wall.

<span class="mw-page-title-main">Rosids</span> Large clade of flowering plants

The rosids are members of a large clade of flowering plants, containing about 70,000 species, more than a quarter of all angiosperms.

<span class="mw-page-title-main">Chloranthaceae</span> Family of flowering plants

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 woody or weakly woody plants occurring in Southeast Asia, the Pacific, Madagascar, Central and South America, and the West Indies. The family consists of four extant genera, totalling about 77 known species according to Christenhusz and Byng in 2016. Some species are used in traditional medicine. The type genus is Chloranthus. The fossil record of the family, mostly represented by pollen such as Clavatipollenites, extends back to the dawn of the history of flowering plants in the Early Cretaceous, and has been found on all continents.

<i>Didymeles</i> Genus of trees

Didymeles is a genus of flowering plants. It is variously treated as the only genus of the family Didymelaceae — or in the family Buxaceae, as in the APG IV system.

Plant taxonomy is the science that finds, identifies, describes, classifies, and names plants. It is one of the main branches of taxonomy.

The APG II system of plant classification is the second, now obsolete, version of a modern, mostly molecular-based, system of plant taxonomy that was published in April 2003 by the Angiosperm Phylogeny Group. It was a revision of the first APG system, published in 1998, and was superseded in 2009 by a further revision, the APG III system.

<span class="mw-page-title-main">Magnoliids</span> Clade of flowering plants

Magnoliids, 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 angiosperms after the eudicots and monocots. The group is characterized by trimerous flowers, pollen with one pore, and usually branching-veined leaves.

<span class="mw-page-title-main">Basal angiosperms</span> Descendants of most extant flowering plants

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, Nymphaeales and Austrobaileyales.

<span class="mw-page-title-main">Mesangiospermae</span> One of two clades of flowering plants

Mesangiospermae is a clade of flowering plants (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. There are about 350,000 species of mesangiosperms. The mesangiosperms contain about 99.95% of the flowering plants, assuming that there are about 175 species not in this group and about 350,000 that are. While such a clade with a similar circumscription exists in the APG III system, it was not given a name.

<span class="mw-page-title-main">Superrosids</span> Clade of flowering plants

The superrosids are members of a large clade of flowering plants, containing more than 88,000 species, and thus more than a quarter of all angiosperms.

<span class="mw-page-title-main">Pentapetalae</span> Group of eudicots known as core eudicots

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. They comprise an extremely large and diverse group accounting for about 65% of the species richness of the angiosperms, with wide variability in habit, morphology, chemistry, geographic distribution, and other attributes. Classical systematics, based solely on morphological information, was not able to recognize this group. In fact, the circumscription of the Pentapetalae as a clade is based on strong evidence obtained from DNA molecular analysis data.

<span class="mw-page-title-main">Superasterids</span> Clade of flowering plants

The superasterids are members of a large clade of flowering plants, containing more than 122,000 species.

References

  1. ↑ "EUDICOTS". Basic Biology. Basic Biology 2020. Retrieved 6 July 2020.
  2. ↑ Endress, Peter K. (2002). "Morphology and Angiosperm Systematics in the Molecular Era" (PDF). Botanical Review. Structural Botany in Systematics: A Symposium in Memory of William C. Dickison. 68 (4): 545–570. doi:10.1663/0006-8101(2002)068[0545:maasit]2.0.co;2. JSTOR   4354438. S2CID   39486751.
  3. ↑ Furness, Carol A.; Rudall, Paula J. (March 2004). "Pollen aperture evolution – a crucial factor for eudicot success?". Trends in Plant Science. 9 (3): 154–158. doi:10.1016/j.tplants.2004.01.001. PMID   15003239.
  4. ↑ Phokas, A.; Coates, J. C. (2021). "Evolution of DELLA function and signaling in land plants". Evolution & Development. 23 (3): 137–154. doi:10.1111/ede.12365. PMC   9285615 . PMID   33428269.
  5. 1 2 Judd & Olmstead 2004
  6. ↑ Sporne, Kenneth R. (1972). "Some Observations on the Evolution of Pollen Types in Dicotyledons". New Phytologist. 71 (1): 181–5. doi: 10.1111/j.1469-8137.1972.tb04826.x .
  7. ↑ Davis, Owen (1999). "Pollen Aperture Definitions". University of Arizona - Geosciences. Archived from the original on 2009-02-03. Retrieved 2009-02-16.
  8. ↑ Worberg, A; Quandt, D; Barniske, A-M; Löhne, C; Hilu, KW; Borsch, T (2007). "Phylogeny of basal eudicots: insights from non-coding and rapidly evolving DNA". Organisms Diversity & Evolution. 7 (1): 55–77. doi: 10.1016/j.ode.2006.08.001 .
  9. ↑ Soltis, Douglas E.; Soltis, Pamela S.; Endress, Peter K.; Chase, Mark W. (2005). Phylogeny and Evolution of Angiosperms. Sunderland, MA: Sinauer Associates. ISBN   9780878938179.
  10. ↑ Moore, Michael J.; Soltis, Pamela S.; Bell, Charles D.; Burleigh, J. Gordon & Soltis, Douglas E. (2010). "Phylogenetic analysis of 83 plastid genes further resolves the early diversification of eudicots". Proceedings of the National Academy of Sciences. 107 (10): 4623–8. Bibcode:2010PNAS..107.4623M. doi: 10.1073/pnas.0907801107 . PMC   2842043 . PMID   20176954.
  11. ↑ Based on:
    Stevens, P.F. (2001–2014). "Trees". Angiosperm Phylogeny Website. Retrieved 2014-11-17.
    Stevens, P.F. (2001–2016). "Eudicots". Angiosperm Phylogeny Website. Retrieved 2014-11-17.
  12. ↑ Angiosperm Phylogeny Group (2016). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV". Botanical Journal of the Linnean Society. 181 (1): 1–20. doi: 10.1111/boj.12385 .

Bibliography

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