Editing Dicotyledon

{{Short description|Historical grouping of flowering plants}}
{{Paraphyletic group
| image = Lamium album (1).JPG
| image_caption = ''[[Lamium album]]'' (white dead nettle)
| auto = yes
| parent = Angiosperms
| includes = * [[Eudicots]]
* [[Magnoliids]]
* ''[[Amborella]]''
* [[Nymphaeales]]
* [[Austrobaileyales]]
* [[Chloranthales]]
* ''[[Ceratophyllum]]''
| excludes = * [[Monocots]]
| synonyms = * Dicotyledoneae
* Magnoliatae <small>[[Takht.]]</small><ref name=Takh64/>
}}

[[File:Dicotyledon plant-let.jpg|thumb|Dicotyledon plantlet]]
[[File:Young castor bean plant showing prominent cotyledons.jpg|thumb|200px|Young [[castor oil plant]] showing its prominent two embryonic leaves ([[cotyledon]]s), which differ from the adult leaves]]

The '''dicotyledons''', also known as '''dicots''' (or, more rarely, '''dicotyls'''),<ref name=TFD/> are one of the two groups into which all the [[flowering plant]]s (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 [[cotyledon]]s. There are around 200,000&nbsp;[[species]] within this group.<ref name=Hamilton2006/> The other group of flowering plants were called [[monocotyledon]]s (or monocots), typically each having one cotyledon. Historically, these two groups formed the two divisions of the flowering plants.

Largely from the 1990s onwards, [[molecular phylogenetics|molecular phylogenetic]] research confirmed what had already been suspected: that dicotyledons are not a group made up of all the descendants of a common ancestor (i.e., they are not a [[monophyly|monophyletic]] group). Rather, a number of lineages, such as the [[magnoliids]] and groups now collectively known as the [[basal angiosperms]], diverged earlier than the monocots did; in other words, monocots evolved from within the dicots, as traditionally defined. The traditional dicots are thus a [[paraphyly|paraphyletic]] group.<ref name=Simp11/>

The [[eudicots]] are the largest monophyletic group within the dicotyledons. They are distinguished from all other flowering plants by the structure of their [[pollen]]. Other dicotyledons and the monocotyledons have [[monosulcate]] pollen (or derived forms): grains with a single sulcus. Contrastingly, eudicots have [[Pollen|tricolpate]] pollen (or derived forms): grains with three or more pores set in furrows called colpi.

==Comparison with monocotyledons==
Aside from [[cotyledon]] number, other broad differences have been noted between [[monocots]] and dicots, although these have proven to be differences primarily between monocots and [[eudicots]]. Many early-diverging dicot groups have monocot characteristics such as scattered [[vascular bundles]], trimerous flowers, and non-tricolpate [[pollen]].<ref name=UCB/> In addition, some monocots have dicot characteristics such as [[Leaf#Venation (arrangement of the veins)|reticulated leaf veins]].<ref name=UCB/>

{| class="wikitable"
|-
! Feature
! In monocots
! In dicots
|-
| Number of parts of each flower
| In threes (flowers are trimerous)
| In fours or fives (tetramerous or pentamerous)
|-
| Number of [[Pollen#Structure|furrows or pores]] in pollen
| One
| Three
|-
| Number of [[cotyledon]]s (leaves in the seed)
| One (Many [[orchids]] are [[acotyledonous]]).
| Two (Some exceptions, including [[Psittacanthus schiedeanus]] with twelve.<ref>{{cite book | last= Kuijt |first= Job | date= 1969 | title= The Biology of Parasitic Plants| location= Berkeley, Calif. | publisher= University of California Press | page= 39 }}</ref>
|-
| Arrangement of vascular bundles in the [[Plant stem|stem]]
| Scattered
| In concentric circles
|-
| Roots
| Are [[adventitious]]
| Develop from the [[radicle]]
|-
| Arrangement of major [[leaf#Veins|leaf veins]]
| [[Parallel (geometry)|Parallel]]
| [[Glossary of botanical terms#reticulate|Reticulate]]
|-
| [[Secondary growth]]
| Absent
| Often present
|-
| [[Stomata]]
| Present on both the upper and lower epidermis of leaves
| More common on the lower epidermis of leaves
|}

{{multiple image
| header    = Comparison of monocots and dicots
| align     = center
| image1    = Monocot vs Dicot.svg
| caption1  =
| alt1      = Illustrations of differences between monocots and dicots
| width1    = 450
}}

== Classification ==
===Phylogeny===
The consensus [[phylogenetic tree]] used in the [[APG IV system]] shows that the group traditionally treated as the dicots is [[Paraphyly|paraphyletic]] to the monocots:<ref name=Cole17/><ref name=APGIV/>
{{clade |style=font-size:100%;line-height:110%;
|label1=[[angiosperms]]
|grouplabel1=traditional dicots
|1={{clade
   |1=[[Amborellales]]|barbegin1=black
   |2={{clade
      |1=[[Nymphaeales]]|bar1=black
      |2={{clade
         |1=[[Austrobaileyales]]|bar1=black
         |label2=[[core angiosperms]]
         |2={{clade
            |1=[[Chloranthales]]|bar1=black
            |2=[[magnoliids]]|bar2=black
            |3={{clade
               |1={{clade
                  |1=[[Ceratophyllales]]&nbsp;|bar1=black
                  |2=[[eudicots]]|barend2=black
                  }}
               |2=[[monocots]]
               }}
            }}
         }}
      }}
   }}
}}

===Historical===
Traditionally, the dicots have been called the Dicotyledones (or ''Dicotyledoneae''), at any rank. If treated as a class, as they are within the [[Cronquist system]], they could be called the Magnoliopsida after the [[type (botany)|type genus]] ''[[Magnolia]]''. In some schemes, the eudicots were either treated as a separate [[class (biology)|class]], the [[Rosopsida]] (type genus ''Rosa''), or as several separate classes. The remaining dicots ([[palaeodicots]] or basal angiosperms) may be kept in a single [[paraphyletic]] class, called [[Magnoliopsida]], or further divided. Some botanists prefer to retain the dicotyledons as a valid class, arguing its practicality and that it makes evolutionary sense.<ref name=Stuessy10/>

===APG vs. Cronquist===
The following lists show the orders in the Angiosperm Phylogeny Group [[APG IV system]] traditionally called dicots,<ref name=APGIV/> together with the older [[Cronquist system]].
{|class=wikitable style="background:transparent;" cellpadding="0" cellspacing="0" align="left"
!align=left|[[APG IV system|APG IV]]<br>(paraphyletic)
!align=left|[[Cronquist system]]<br>(classis '''Magnoliopsida''')
|-
|valign="top"|<!-- APG IV -->
* [[Amborellales]]
* [[Austrobaileyales]]
* [[Nymphaeales]]
* ; [[magnoliids]]
** [[Canellales]]
** [[Laurales]]
** [[Magnoliales]]
** [[Piperales]]
* ; unplaced independent lineage
** [[Chloranthales]]
* ; probable sister of eudicots
** [[Ceratophyllales]]
* ; [[eudicots]]
** [[Buxales]]
** [[Proteales]]
** [[Ranunculales]]
** [[Trochodendrales]]
** ; [[core eudicots]]
*** [[Dilleniales]]
*** [[Gunnerales]]
*** ; [[superrosids]]
**** [[Brassicales]]
**** [[Celastrales]]
**** [[Crossosomatales]]
**** [[Cucurbitales]]
**** [[Fabales]]
**** [[Fagales]]
**** [[Geraniales]]
**** [[Huerteales]]
**** [[Malpighiales]]
**** [[Malvales]]
**** [[Myrtales]]
**** [[Oxalidales]]
**** [[Picramniales]]
**** [[Rosales]]
**** [[Sapindales]]
**** [[Saxifragales]]
**** [[Vitales]]
**** [[Zygophyllales]]
*** ; [[superasterids]]
**** [[Apiales]]
**** [[Aquifoliales]]
**** [[Asterales]]
**** [[Berberidopsidales]]
**** [[Boraginales]]
**** [[Bruniales]]
**** [[Caryophyllales]]
**** [[Cornales]]
**** [[Dipsacales]]
**** [[Ericales]]
**** [[Escalloniales]]
**** [[Garryales]]
**** [[Gentianales]]
**** [[Icacinales]]
**** [[Lamiales]]
**** [[Metteniusales]]
**** [[Paracryphiales]]
**** [[Santalales]]
**** [[Solanales]]
**** [[Vahliales]]
|valign="top"|<!-- Cronquist -->
::;[[Magnoliids|Magnoliidae]] (mostly basal dicots)
:::* [[Magnoliales]]
:::* [[Laurales]]
:::* [[Piperales]]
:::* [[Aristolochiaceae|Aristolochiales]]
:::* [[Austrobaileyales|Illiciales]]
:::* [[Nymphaeales]]
:::* [[Ranunculales]]
:::* [[Ranunculales|Papaverales]]
::;[[Hamamelidae]]
:::* [[Trochodendrales]]
:::* [[Hamamelidales]]
:::* [[Daphniphyllum|Daphniphyllales]]
:::* [[Didymeles|Didymelales]]
:::* [[Eucommia]]les
:::* [[Urticales]]
:::* [[Leitneriales]]
:::* [[Juglandales]]
:::* [[Myricales]]
:::* [[Fagales]]
:::* [[Casuarinaceae|Casuarinales]]
::;[[Caryophyllidae]]
:::* [[Caryophyllales]]
:::* [[Polygonaceae|Polygonales]]
:::* [[Plumbaginaceae|Plumbaginales]]
::;[[Dilleniidae]]
:::* [[Dilleniales]]
:::* [[Theales]]
:::* [[Malvales]]
:::* [[Lecythidales]]
:::* [[Nepenthales]]
:::* [[Violales]]
:::* [[Salicaceae|Salicales]]
:::* [[Capparales]]
:::* [[Batales]]
:::* [[Ericales]]
:::* [[Diapensiales]]
:::* [[Ebenales]]
:::* [[Primulales]]
::;[[Rosidae]]
:::* [[Rosales]]
:::* [[Fabales]]
:::* [[Proteales]]
:::* [[Podostemales]]
:::* [[Haloragales]]
:::* [[Myrtales]]
:::* [[Rhizophoraceae|Rhizophorales]]
:::* [[Cornales]]
:::* [[Santalales]]
:::* [[Rafflesiales]]
:::* [[Celastrales]]
:::* [[Euphorbiales]]
:::* [[Rhamnales]]
:::* [[Linales]]
:::* [[Polygalales]]
:::* [[Sapindales]]
:::* [[Geraniales]]
:::* [[Apiales]]
::;[[Asteridae]]
:::* [[Gentianales]]
:::* [[Solanales]]
:::* [[Lamiales]]
:::* [[Callitrichales]]
:::* [[Plantaginales]]
:::* [[Scrophulariales]]
:::* [[Campanulales]]
:::* [[Rubiales (plant)|Rubiales]]
:::* [[Dipsacales]]
:::* [[Calycerales]]
:::* [[Asterales]]
|}
{{Clear}}

===Dahlgren and Thorne systems===
Under the Dahlgren and Thorne systems, the [[Subclass (biology)|subclass]] name ''Magnoliidae'' was used for the dicotyledons. This is also the case in some of the systems derived from the Cronquist system.{{cn|date=June 2024}} These two systems are contrasted in the table below in terms of how each categorises by superorder; note that the sequence within each system has been altered in order to pair corresponding taxa

The [[Thorne system (1992)|Thorne system (1992) as depicted by Reveal]] is:
{| class="wikitable sortable" align="left" style="margin-left: auto; margin-right: auto"
!style="background:lightgreen" align="center"| [[Dahlgren system]]
!style="background:lightgreen" align="center"| [[Thorne system]]
|-
| [[Magnolianae]]<br />
[[Ranunculanae]]
| [[Magnolianae]]<br />
[[Rafflesianae]]
|-
| [[Nymphaeanae]]
| [[Nymphaeanae]]
|-
| [[Caryophyllanae]]
| [[Caryophyllanae]]
|-
| [[Theanae]]<br />
[[Plumbaginanae]]<br />
[[Polygonanae]]<br />
[[Primulanae]]<br />
[[Ericanae]]
| [[Theanae]]
|-
| [[Malvanae]]
| [[Malvanae]]
|-
| [[Violanae]]
| [[Violanae]]
|-
| [[Rosanae]]
| [[Rosanae]]
|-
| [[Proteanae]]
| [[Proteanae]]
|-
| [[Myrtanae]]
| [[Myrtanae]]
|-
| [[Rutanae]]
| [[Rutanae]]<br />
[[Celastranae]]<br />
[[Geranianae]]
|-
| [[Santalanae]]
| [[Santalanae]]
|-
| [[Balanophoranae]]
| [[Santalanae]]
|-
| [[Asteranae]]
| [[Asteranae]]
|-
| [[Solananae]]
| [[Solananae]]
|-
| [[Cornanae]]<br />
[[Vitanae]]
| [[Cornanae]]<br />
[[Aralianae]]
|-
| [[Loasanae]]
| [[Loasanae]]
|-
| [[Gentiananae]]<br />
[[Lamianae]]
| [[Gentiananae]]
|}
{{clear}}
There exist variances between the superorders [[Circumscription (taxonomy)|circumscribed]] from each system. Namely, although the systems share common names for many of the listed superorders, the specific list orders classified within each varies. For example, Thorne's ''Theanae'' corresponds to five distinct superorders under Dahlgren's system, only one of which is called ''Theanae.''{{Clear}}

==See also==
* [[Calyciflorae]]

==References==
{{Reflist|refs=
<ref name=APGIV>{{Citation |last=Angiosperm Phylogeny Group  |year=2016 |title=An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV |journal=[[Botanical Journal of the Linnean Society]] |volume=181 |issue=1 |pages=1–20 |doi=10.1111/boj.12385 |ref={{harvid|APG IV|2016}} |doi-access=free }}</ref>

<ref name=Cole17>{{citation |last1=Cole |first1=Theodor C.H. |last2=Hilger |first2=Hartmut H. |last3=Stevens |first3=Peter F. |title=Angiosperm Phylogeny Poster - Flowering Plant Systematics |date=2017 |url=http://www2.biologie.fu-berlin.de/sysbot/poster/poster1.pdf |access-date=2017-07-13 |name-list-style=amp |archive-date=2017-05-17 |archive-url=https://web.archive.org/web/20170517030259/http://www2.biologie.fu-berlin.de/sysbot/poster/poster1.pdf |url-status=dead }}</ref>

<ref name=Hamilton2006>{{Citation | last1 = Hamilton | first1 = Alan| last2 = Hamilton | first2 = Patrick| year = 2006| title = Plant conservation: An ecosystem approach| pages = 2| url = https://books.google.com/books?id=P6m0OTheY8sC| isbn = 978-1-84407-083-1| publisher = Earthscan| location = London }}</ref>

<ref name=Simp11>{{Citation |first1=Michael G. |last1=Simpson |title=Plant Systematics |publisher=Elsevier |year=2011 |chapter=Chapter 7: Diversity and Classification of Flowering Plants |page=139 |isbn=978-0-0805-1404-8}}</ref>

<ref name=Stuessy10>{{citation | last1 = Stuessy | first1 = Tod F. | year = 2010 | title = Paraphyly and the origin and classification of angiosperms. | journal = Taxon | volume = 59 | issue = 3 |  pages = 689–693 |url=http://www.ktriop.bio.ug.edu.pl/upload/preview/d866ba1ba9b0c1ed4b27a44373a5e40b.pdf| doi = 10.1002/tax.593001 }}</ref>

<ref name=Takh64>{{citation |last1=Takhtajan |first1=A. |author-link=Takhtajan |title=The Taxa of the Higher Plants above the Rank of Order |journal=[[Taxon (journal)|Taxon]] |date=June 1964 |volume=13 |issue=5 |pages=160–164 |doi=10.2307/1216134 |jstor=1216134 }}</ref>

<ref name=TFD>{{citation |title=Dicotyl |work=The Free Dictionary |url=http://www.thefreedictionary.com/dicotyl |access-date=2 January 2016}}</ref>

<ref name=UCB>{{citation |title=Monocots versus Dicots |url=http://www.ucmp.berkeley.edu/glossary/gloss8/monocotdicot.html |publisher=[[University of California Museum of Paleontology]] |access-date=25 January 2012}}</ref>
}}

{{Wikispecies|Magnoliopsida}}

==External links==
{{Wikispecies|Magnoliopsida}}
* [http://www.catalogueoflife.org/annual-checklist/2019/browse/classification/class/Magnoliopsida/fossil/1/match/1 World list of dicot species (a.k.a. Magnoliopsida) from the Catalogue of Life], 253,406 species.
* [http://www.catalogueoflife.org/annual-checklist/2019/browse/tree/id/53497bb664b89c28e60f020f7f21f882 Tree browser for dicot orders, families and genera with species counts and estimates via the Catalogue of Life]

{{Taxonbar|from=Q8316}}
{{Authority control}}

[[Category:Historically recognized angiosperm taxa]]