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Moved Taxonomy heading to match template order

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{{Short description|Species of flowering plants in the daisy family Asteraceae}}
{{Speciesbox
|name = Russian knapweed
|image = Acroptilon repens.jpg
|display_parents = 2
|genus = Rhaponticum
|species = repens
|authority = ([[Carl Linnaeus|L.]]) [[Oriane Hidalgo|Hidalgo]]<ref name=POWO_77073843-1/>
|synonyms =
{{Species list
|Acroptilon angustifolium|Cass.
|Acroptilon australe|Iljin
|Acroptilon obtusifolium|Cass.
|Acroptilon picris|(Pall. ex Willd.) C.A.Mey.
|Acroptilon repens|(L.) DC.
|Acroptilon repens subsp. australe|(Iljin) Rech.f.
|Acroptilon serratum|Cass.
|Acroptilon subdentatum|Cass.
|Carduus picris|(Pall. ex Willd.) Sweet
|Centaurea picris|Pall. ex Willd.
|Centaurea repens|L.
|Leuzea repens|(L.) D.J.N.Hind
|Serratula amara|Pall.
|Serratula picris|(Pall. ex Willd.) M.Bieb.
}}
|synonyms_ref = <ref name="POWO_77073843-1">{{cite web |title=''Rhaponticum repens'' (L.) Hidalgo |work=Plants of the World Online |publisher=Royal Botanic Gardens, Kew|url=http://www.plantsoftheworldonline.org/taxon/urn:lsid:ipni.org:names:77073843-1 |access-date=2023-11-06 }}</ref>
|}}

'''''Rhaponticum repens''''', [[Synonym (taxonomy)|synonyms]] including '''''Acroptilon repens''''' and '''''Leuzea repens''''',<ref name=POWO_77073843-1/> with the common name '''Russian knapweed''', is a species of bushy [[rhizome|rhizomatous]] perennial belonging to the family [[Asteraceae]].

== Description ==
Russian knapweed is a deep-rooted long-lived perennial. Some stands have been in existence for 75 years. It forms dense colonies in cultivated fields, orchards, pastures, and roadsides.

The [[Habit (biology)|habit]] grows up to 80 cm tall.

Stems and leaves are finely arachnoid-tomentose becoming glabrous and green with age. The rosette leaves are oblanceolate, pinnately lobed to entire, 2–3 cm wide by 3–8 cm long. The lower cauline leaves are smaller, pinnately lobed; the upper leaves become much reduced, sessile, serrate to entire.

The heads are numerous terminating the branches. Flowers are pink to purplish, the marginal ones not enlarged. The outer and middle involucral bracts are broad, [[striate]], smooth with broadly rounded tips; the inner bracts are narrower with hairy tips. [[Pappus (botany)|Pappus]] present with bristles 6–11mm long. Fruit is a whitish, slightly ridged achene.

==Taxonomy==
The species was first described by [[Carl Linnaeus]] in 1763 as ''Centaurea repens''.<ref name="TPL_gcc-4803">{{cite web |title=''Centaurea repens'' |url=http://www.theplantlist.org/tpl1.1/record/gcc-4803 |accessdate=2015-02-26 |work=The Plant List}}</ref><ref name="IPNI_Centaurea_repens">{{cite web |title=IPNI Plant Name Query Results for ''Centaurea repens'' |url=http://www.ipni.org/ipni/simplePlantNameSearch.do?find_wholeName=Centaurea+repens |accessdate=2015-02-26 |work=[[International Plant Names Index|The International Plant Names Index]]}}</ref><ref>{{cite book |author=Carl Linnaeus |author-link=Carl Linnaeus |url=http://www.botanicus.org/item/31753000803525 |title=Species plantarum :exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas |year=1763 |edition=2 |volume=2 |page=1293 |chapter=''Centaurea'' 28 ''repens'' |chapter-url=http://www.botanicus.org/page/1165706}}</ref> [[Augustin Pyramus de Candolle]] separated it from the genus ''[[Centaurea]]'' in 1838, placing it in the genus ''Acroptilon''.<ref name="IPNI_Centaurea_repens" /> The genus name derives from ''acro-'' (high, here meaning tip) and ''ptilo-'' (feather).<ref name="FNA">{{cite web |title=Acroptilon |url=http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=100387 |work=[[Flora of North America]]}}</ref> A 1995 [[Molecular phylogenetics|molecular phylogenetic]] study, the structure of the flower, and the [[chromosome number]] support separating it from the genus ''[[Centaurea]]''. Some sources then continue to place it as the sole member of the monotypic genus ''Acroptilon''.<ref name="FNA" /> A phylogenetic study published in 2006 concluded that ''Acroptilon'' belongs in the genus ''Rhaponticum''.<ref name="HidaGarcGarnSusa06">{{cite journal |last1=Hidalgo |first1=O. |last2=Garcia-Jacas |first2=N |last3=Garnatje |first3=T |last4=Susanna |first4=A |year=2006 |title=Phylogeny of Rhaponticum (Asteraceae, Cardueae-Centaureinae) and Related Genera Inferred from Nuclear and Chloroplast DNA Sequence Data: Taxonomic and Biogeographic Implications |journal=Annals of Botany |volume=97 |issue=5 |pages=705–14 |doi=10.1093/aob/mcl029 |pmc=2803413 |pmid=16495316}}</ref>
== Distribution ==
A native to [[Eurasia]], Russian knapweed was introduced into North America in the late 19th century. Absent only from southeastern U.S., it has become widespread in other regions, especially in the western United States.<ref>{{cite web | title = Acroptilon repens | url = http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=200023016 | work = [[Flora of North America]]}}</ref>

== Toxicity ==
[[Nigropallidal encephalomalacia]], also called ''chewing disease'', a movement disorder similar to Parkinson's disease, is caused in horses ingesting Russian knapweed for prolonged periods. A [[sesquiterpene lactone]], repin, in the plant is likely responsible for this toxicity.<ref>{{cite journal |doi=10.1002/(SICI)1097-4547(19970101)47:1<90::AID-JNR10>3.0.CO;2-E |pmid=8981242 |title=Cytotoxic effects of repin, a principal sesquiterpene lactone of russian knapweed |journal=Journal of Neuroscience Research |volume=47 |issue=1 |pages=90–7 |year=1997 |last1=Robles |first1=M. |last2=Wang |first2=N. |last3=Kim |first3=R. |last4=Choi |first4=B.H. |s2cid=23156210 }}</ref>
[[File:Acroptilon repens absnd.jpg|thumb|Russian knapweed in Mashhad-Iran]]
==References==
{{Reflist}}

==External links==
*[http://ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?609,621,622 Jepson Manual Treatment]
*[https://www.invasivespeciesinfo.gov/profile/russian-knapweed Species Profile- Russian Knapweed (''Rhaponticum repens'')], National Invasive Species Information Center, [[United States National Agricultural Library]]. Lists general information and resources for Russian Knapweed.

{{Taxonbar|from1=Q15551896|from2=Q89024824|from3=Q12846085|from4=Q25531399}}

[[Category:Cardueae]]
[[Category:Flora of temperate Asia]]
[[Category:Flora of Europe]]
[[Category:Plants described in 1763]]

Rhaponticum repens - Revision history

imported>FloppaDude: Moved Taxonomy heading to match template order