WordNet

flowering plant with two cotyledons; the stem grows by deposit on its outside (同)dicotyledon, magnoliopsid, exogen
(of a flowering plant) having two cotyledons in the seed

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双子葉植物

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/09/05 06:06:21」(JST)

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Young castor oil plant showing its prominent two embryonic leaves (cotyledons), that differ from the adult leaves.

The dicotyledons, also known as dicots (or more rarely dicotyls^[1]) were one of the two groups into which all the flowering plants or angiosperms were formerly divided. The name refers to one of the typical characteristics of the group, namely that the seed typically has two embryonic leaves or cotyledons. There are around 200,000 species within this group.^[2] The other group of flowering plants were called monocotyledons or monocots, typically having one cotyledon. Historically, these two groups formed the two divisions of the flowering plants.

Largely from the 1990s onwards, molecular phylogenetic research confirmed what had already been suspected, namely that dicotyledons are not a group made up of all the descendants of a common ancestor (i.e. they are not a 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. The traditional dicots are thus a paraphyletic group. The largest clade of the dicotyledons are known as the eudicots. They are distinguished from all other flowering plants by the structure of their pollen. Other dicotyledons and monocotyledons have monosulcate pollen, or forms derived from it, whereas eudicots have tricolpate pollen, or derived forms, the pollen having three or more pores set in furrows called colpi.

Compared to 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.^[3] In addition, some monocots have dicot characteristics such as reticulated leaf veins.^[3]

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 furrows or pores in pollen	One	Three
Number of cotyledons (leaves in the seed)	One	Two
Arrangement of vascular bundles in the stem	Scattered	In concentric circles
Roots	Are adventitious	Develop from the radicle
Arrangement of major leaf veins	Parallel	Reticulate
Secondary growth	Absent	Often present

Classification

Historical

Traditionally the dicots have been called the Dicotyledones (or Dicotyledoneae), at any rank. If treated as a class, as in the Cronquist system, they could be called the Magnoliopsida after the type genus Magnolia. In some schemes, the eudicots were treated as a separate 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.^[4]

APG (Angiosperm Phylogeny Group) vs. Cronquist Classification

The following lists show the orders in the APG III system traditionally called dicots,^[5] together with the older Cronquist system.

APG III (polyphyletic)	Cronquist system (classis Magnoliopsida)
Amborellales Nymphaeales Austrobaileyales Chloranthales magnoliids Canellales Laurales Magnoliales Piperales eudicots Sabiaceae Buxales Proteales Ranunculales Trochodendrales core eudicots Dilleniaceae Gunnerales Saxifragales Berberidopsidales Caryophyllales Santalales rosids Vitales fabids (eurosids I) Celastrales Cucurbitales Fabales Fagales Malpighiales Oxalidales Rosales Zygophyllales malvids (eurosids II) Brassicales Crossosomatales Geraniales Huerteales Malvales Myrtales Picramniales Sapindales asterids Cornales Ericales lamiids (euasterids I) Boraginaceae Vahliaceae Icacinaceae Metteniusaceae Oncothecaceae Garryales Gentianales Lamiales Solanales campanulids (euasterids II) Apiales Aquifoliales Asterales Bruniales Dipsacales Escalloniales Paracryphiales	Magnoliidae (mostly basal dicots) Magnoliales Laurales Piperales Aristolochiales Illiciales Nymphaeales Ranunculales Papaverales Hamamelidae Trochodendrales Hamamelidales Daphniphyllales Didymelales Eucommiales Urticales Leitneriales Juglandales Myricales Fagales Casuarinales Caryophyllidae Caryophyllales Polygonales Plumbaginales Dilleniidae Dilleniales Theales Malvales Lecythidales Nepenthales Violales Salicales Capparales Batales Ericales Diapensiales Ebenales Primulales Rosidae Rosales Fabales Proteales Podostemales Haloragales Myrtales Rhizophorales Cornales Santalales Rafflesiales Celastrales Euphorbiales Rhamnales Linales Polygalales Sapindales Geraniales Apiales Asteridae Gentianales Solanales Lamiales Callitrichales Plantaginales Scrophulariales Campanulales Rubiales Dipsacales Calycerales Asterales

Dahlgren and Thorne systems

In the Dahlgren and the Thorne systems, the subclass name Magnoliidae was used for the dicotyledons. This is also the case in some of the systems derived from the Cronquist system. For each system, only the superorders are listed. The sequence of each system has been altered to pair corresponding taxa, although circumscription of superorders with the same name is not always the same. The Thorne system (1992) as depicted by Reveal is:

**Comparison of the Dahlgren and Thorne systems**
Dahlgren system	Thorne system
Magnolianae Ranunculanae	Magnolianae Rafflesianae
Nymphaeanae	Nymphaeanae
Caryophyllanae	Caryophyllanae
Theanae Plumbaginanae Polygonanae Primulanae Ericanae	Theanae
Malvanae	Malvanae
Violanae	Violanae
Rosanae	Rosanae
Proteanae	Proteanae
Myrtanae	Myrtanae
Rutanae	Rutanae Celastranae Geranianae
Santalanae	Santalanae
Balanophoranae	Santalanae
Asteranae	Asteranae
Solananae	Solananae
Cornanae Vitanae	Cornanae Aralianae
Loasanae	Loasanae
Dicotyledons	Gentiananae Lamianae	Gentiananae

References

^ "Dicotyl". The Free Dictionary. Retrieved 2-15-08-14. Check date values in: |accessdate= (help)
^ Hamilton, Alan; Hamilton, Patrick (2006), Plant conservation : an ecosystem approach, London: Earthscan, p. 2, ISBN 978-1-84407-083-1
^ ^a ^b "Monocots versus Dicots". University of California Museum of Paleontology. Retrieved 25 January 2012.
^ Stuessy, Tod F. (2010). "Paraphyly and the origin and classification of angiosperms." (PDF). Taxon 59: 689–693.
^ Angiosperm Phylogeny Group (2009), "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III", Botanical Journal of the Linnean Society 161 (2): 105–121, doi:10.1111/j.1095-8339.2009.00996.x, retrieved 2010-12-10

English Journal

On the move: induced resistance in monocots.

Balmer D1, Planchamp C, Mauch-Mani B.
Journal of experimental botany.J Exp Bot.2013 Mar;64(5):1249-61. doi: 10.1093/jxb/ers248. Epub 2012 Oct 1.
Although plants possess an arsenal of constitutive defences such as structural barriers and preformed antimicrobial defences, many attackers are able to overcome the pre-existing defence layers. In response, a range of inducible plant defences is set up to battle these pathogens. These mechanisms, c
PMID 23028020

Natural rubber biosynthesis in plants: rubber transferase.

Cornish K1, Xie W.
Methods in enzymology.Methods Enzymol.2012;515:63-82. doi: 10.1016/B978-0-12-394290-6.00004-5.
Rubber biosynthesis in plants is a fascinating biochemical system, which evolved at the dawn of the dicotyledoneae and is present in at least four of the dictolydonous superorders. Rubber biosynthesis is catalyzed by a membrane complex in a monolayer membrane envelope, requires two distinct substrat
PMID 22999170

Germination inhibitor from the Japanese cedar Cryptomeria japonica.

Chen XH1, Kashiwagi T, Tebayashi S, Kim CS.
Zeitschrift für Naturforschung. C, Journal of biosciences.Z Naturforsch C.2005 Jan-Feb;60(1-2):79-82.
(1S,6R)-2,7(14),10-Bisabolatrien-1-ol-4-one was identified as a germination inhibitor from the methanol extract of Japanese cedar wood, Cryptomeria japonica. The occurrence of this compound in 1 g fresh wood was 2.0 mg, and showed a maximum of 60% germination inhibition at the dose of 20 mg/filter p
PMID 15787249

Japanese Journal

SieboldとZuccariniが日本から記載した分類群のレクトタイプと原資料(第2部)被子植物双子葉植物綱(1)

秋山忍,THIJSSE Gerard,ESSER Hans-Joachim [他]
植物研究雑誌 88(6), 346-377, 2013-12
NAID 40019923979

喜界島の植物

木戸伸栄,キドノブヨシ,Kido Nobuyoshi
福祉社会学部論集 31(3), 1-17, 2012-12
… Plants of Kikaijima are 87 family 251species(Pteridophyta 6family11species, Gymnospermae 4family 6species, Dicotyledoneae 63 family180species, Monocotyledoneae 14family 55species)Special plants are Euphorbia adenochlora, Ischaemum aureum, Lotusaustralis, Vigna marina, Sesuvium portulacastrum, Toddalia asiatica onthe coral limestone …
NAID 120005350027

出水市蕨島の植物

木戸伸栄,キドノブヨシ,Kido Nobuyoshi
福祉社会学部論集 31(2), 32-43, 2012-10
… Plannts of Nagashiraa island are 80 family 229species (Pteridophyta5faraily 16species,Gyranosperraae 5family 5species,Dicotyledoneae59family 167species, Monocotyledoneae llfamily 41species)Special plants are Hibiscus hamabo, Cyperus malaccensis ssp.monophyllus …
NAID 120005350025

Related Pictures

★リンクテーブル★

リンク元	「双子葉類」「dicot」「双子葉植物」「dicotyledon」「dicotyledonous」

「双子葉類」

Dicotyledon
	; Lamium album (white dead nettle)
Scientific classification
Kingdom:	Plantae;
(unranked)	Angiosperms;
Included groups
	Eudicot; Magnoliid; Amborella; Nymphaeales; Austrobaileyales; Chloranthales; Ceratophyllum;
Excluded groups
	Monocot;
Synonyms
	Dicotyledoneae;