Xanthium

{{Short description|Genus of plants}} {{Automatic taxobox | image = Xanthium strumarium L..jpg | image_caption = ''[[Xanthium strumarium]]'' | display_parents = 3 | taxon = Xanthium | authority = [[Carl Linnaeus|L.]] | type_species_authority = [[Carl Linnaeus|L.]] | type_species = ''[[Xanthium strumarium]]''<ref>lectotype designated by J.P. Fourreau, Ann. Soc. Linn. Lyon ser. 2 17: 110 (1869)</ref><ref name=n>[http://www.tropicos.org/Name/40026941 Tropicos, ''Xanthium'' L.]</ref> | synonyms_ref = <ref name=g/> | synonyms = * ''Xanthium'' sect. ''Euxanthium'' DC. * ''Acanthoxanthium'' (DC.) Fourr. * ''Xanthium'' sect. ''Acanthoxanthium'' DC. }}

'''''Xanthium''''' ('''cocklebur''') is a [[genus]] of [[flowering plant]]s in the tribe [[Heliantheae]] within the family [[Asteraceae]], native to the [[Americas]] and eastern [[Asia]] and some parts of south Asia.<ref name=n/><ref name=g/><ref>[https://www.biodiversitylibrary.org/page/359008#page/429/mode/1up Linnaeus, Carl von. 1753. ''Species Plantarum'' 2: 987] in Latin</ref>

==Description== Cockleburs are coarse, [[herbaceous]] [[annual plant]]s growing to {{convert|20|-|47|in|cm|order=flip|abbr=on|-1}} tall. The leaves are spirally arranged, with deeply toothed margins. Some species, notably ''[[Xanthium spinosum]]'', are also very thorny with long, slender [[Thorns, spines, and prickles|spines]] at the leaf bases.<ref name=r>[http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=135017 ''Flora of North America'' Vol. 21 Page 19, Lampourde, ''Xanthium'' Linnaeus, Sp. Pl. 2: 987. 1753; Gen. Pl. ed. 5, 424. 1754. ]</ref>

The flower heads are of two types; One, in short terminal branches, produces only [[pollen]]. The other, in clusters in the axils of the leaves, produces seed.<ref name=r/>

Unlike many other members of the family [[Asteraceae]], whose seeds are airborne with a plume of silky hairs resembling miniature [[parachute]]s, cocklebur seeds are produced in a hard, spiny, [[globose]] or oval double-chambered, single-seeded bur {{convert|0.32|-|0.79|in|mm|order=flip|abbr=on|0}} long. It is covered with stiff, hooked spines, which stick to fur and clothing and can be quite difficult to detach. These burs are carried long distances from the parent plant during [[seed dispersal]] by help of animals ([[zoochorous]]).<ref>[http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=135017 ''Flora of China'' Vol. 20–21 Page 4, 6, 852, 875 <big>苍耳属</big> cang er shu ''Xanthium'' Linnaeus, Sp. Pl. 2: 987. 1753. ]</ref>

==Biology== Cockleburs are short-day plants, meaning they only initiate flowering when the days are getting shorter in the late summer and fall, typically from July to October in the [[Northern Hemisphere]]. They can also flower in the tropics where the daylength is constant.{{citation needed|date=February 2020}}

==Diversity== Over 200 names have been proposed for species, subspecies, and varieties within the genus. Most of these are regarded as synonyms of highly variable species. Some recognize as few as two or three species in the genus. The Global Compositae Checklist recognizes the following.

;Accepted species<ref name=g>[https://archive.today/20150117084930/http://dixon.iplantcollaborative.org/compositaeweb/default.aspx?Page=NameDetails&TabNum=0&NameId=4c758060-c858-4c96-8d37-e38f806ef0f3 Flann, C (ed) 2009+ "Global Compositae Checklist"]</ref> * ''[[Xanthium albinum]]'' (Widd.) Scholz & Sukopp – [[Mongolia]] * ''[[Xanthium argenteum]]'' Widder – [[Chile]] * ''[[Xanthium catharticum]]'' Kunth – [[Chile]], [[Bolivia]], [[Argentina]] * ''[[Xanthium cavanillesii]]'' [[Joakim Frederik Schouw|Shouw]] – [[Argentina]] * ''[[Xanthium inaequilaterum]]'' [[DC.]] – [[China]], [[India]], [[Southeast Asia]] * ''[[Xanthium mongolicum]]'' Kitag. – [[Mongolia]] * ''[[Xanthium orientale]]'' [[Carl Linnaeus|L.]] – [[Europe]], [[North Africa]], [[Middle East]] * ''[[Xanthium pungens]]'' Wallr. – [[Australia]]; naturalized in [[Eurasia]] * ''[[Xanthium saccharosum]]'' * ''[[Xanthium spinosum]]'' [[Carl Linnaeus|L.]] – spiny cocklebur, burreed, Bathurst burr – very widespread, nearly [[Cosmopolitan distribution|cosmopolitan]] * ''[[Xanthium strumarium]]'' [[Carl Linnaeus|L.]] – clotbur, rough cocklebur, large cocklebur, common cocklebur – very widespread, nearly [[Cosmopolitan distribution|cosmopolitan]]

;formerly included<ref name=g/> * see ''[[Ambrosia (plant)|Ambrosia]]'' * ''Xanthium artemisioides – [[Ambrosia arborescens]]'' * ''Xanthium fruticosum – [[Ambrosia arborescens]]''

==Legal status== The cocklebur is legally listed as a noxious weed in the states of [[Arkansas]] and [[Iowa]] in the United States of America.{{Citation needed|date=February 2020}}

==Toxicity and uses== The common cocklebur (''[[Xanthium strumarium]]'') is a native of [[North America]]. It has become an [[invasive species]] worldwide. It invades agricultural lands and can be poisonous to [[livestock]], including horses, cattle, and sheep. Some domestic animals will avoid consuming the plant if other forage is present, but less discriminating animals, such as pigs, will consume the plants and then sicken and die. The seedlings and seeds are the most toxic parts of the plants. Symptoms usually occur within a few hours, producing unsteadiness and weakness, depression, [[nausea]] and vomiting, twisting of the neck muscles, rapid and weak pulse, difficulty breathing, and eventually death.{{Citation needed|date=February 2020}}

The plant also has been used for making yellow dye, hence the name of the genus (Greek ''xanthos'' means 'yellow'). The many species of this plant, which can be found in many areas, may actually be varieties of two or three species. The [[cocklebur oil|seed oil]] is edible.{{citation needed|date=February 2016}}

''Xanthium strumarium'' is known as ''cang er zi'' (蒼耳子) in [[traditional Chinese medicine]]. ''Xanthium'' is also used to treat nasal and sinus congestion.<ref>{{cite journal|author=English, J.|year=2010|title=Natural Allergy Relief|journal=Nutrition Review|volume=4|issue=2|url=http://www.nutritionreview.org/library/allergy-immune.php|access-date=2012-01-03|archive-date=2012-02-02|archive-url=https://web.archive.org/web/20120202155918/http://nutritionreview.org/library/allergy-immune.php|url-status=dead}}</ref>

The spines and seeds of this fruit are rich in a chemical called [[carboxyatractyloside]] (CAT), formerly referred to as xanthostrumarin, which is the chemical that is responsible for most of the adverse effects from the use of ''cang er zi''. CAT has been shown to be a growth inhibitor in ''Xanthium'' and other plants, serving two functions, delaying seed germination and inhibiting the growth of other plants. Most of the chemical is concentrated in the spines. When the bur is prepared as an herbal remedy, the spines are usually removed, reducing the CAT content of the finished product.<ref>Cutler, H. G. and R. J. Cole. (1983). "Carboxyatractyloside: A compound from ''Xanthium strumarium'' and ''Atractylis gummifera'' with plant growth inhibiting properties". ''Journal of Natural Products'' 46(5) 609-13.</ref>

==Gallery== <gallery> File:Cocklebur Seedling West Texas 2003.jpg|''X. strumarium'' File:Xanthium italicum ENBLA02.JPG|''X. italicum'' File:Szerbtövis.jpg|''X. spinosum'' File:XanthiumAlbinum2.jpg|''X. albinum'' File:Arctium minus 2.jpg|Unidentified ''Xanthium'' </gallery>

==See also== * [[List of beneficial weeds]] * [[List of companion plants]] * [[List of plants poisonous to equines]]

==References== {{Reflist}}

==Further reading== *{{Cite book |last1=Everitt |first1=J.H. |last2=Lonard |first2=R.L. |last3=Little |first3=C.R. |title=Weeds in South Texas and Northern Mexico |publisher=Texas Tech University Press |location=Lubbock |year=2007}} {{ISBN|0-89672-614-2}}

[[Category:Xanthium| ]] [[Category:Asteraceae genera]] [[Category:Medicinal plants of Asia]] [[Category:Medicinal plants of North America]] [[Category:Botanical taxa named by Carl Linnaeus]]