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{{Short description|Species of flowering plant}}
{{Speciesbox
|image = Helenium amarum1.jpg
| status = G5
| status_system = TNC
| status_ref = <ref name="natureserve">{{cite web |title=NatureServe Explorer 2.0 |url=https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.145025/Helenium_amarum |website=explorer.natureserve.org}}</ref>
|genus = Helenium
|species = amarum
|authority = ([[Constantine Samuel Rafinesque|Raf.]]) [[Howard Francis Leonard Rock|H.Rock]]
|synonyms_ref = <ref name=wwww>{{ThePlantList}}</ref><ref>{{Tropicos|50132443|Gaillardia amara}}</ref>
|synonyms = *''Gaillardia amara'' Raf.
* ''Galardia amara'' Raf.
* ''Helenium badium'' (A.Gray ex S.Watson) Greene
}}

'''''Helenium amarum''''' is a species of annual herb in the [[Asteraceae|daisy family]] known by the common names '''yellowdicks''', '''yellow sneezeweed''', '''fiveleaf sneezeweed,''' and '''bitter sneezeweed'''. It is native to much of the south-central United States ([[Texas]], [[Oklahoma]], [[Louisiana]], [[Arkansas]], [[New Mexico]])<ref name=wwwwwww/> and northern Mexico ([[Chihuahua (state)|Chihuahua]], [[Coahuila]]),<ref name=wwwwww/> and it is present elsewhere in North America, Australia, and the West Indies as an [[introduced species]].<ref name=wwwwwww>{{BONAP|ref |genus=Helenium |species=amarum}}</ref><ref>Turner, B. L. 2013. The comps of Mexico. A systematic account of the family Asteraceae (chapter 11: tribe Helenieae). Phytologia Memoirs 16: 1–100.</ref><ref>[http://www.tropicos.org/Name/2700849?tab=specimens Tropicos, specimen listing for ''Helenium amarum'' (Raf.) H. Rock ]</ref><ref>[https://www.daf.qld.gov.au/plants/weeds-pest-animals-ants/weeds/a-z-listing-of-weeds/photo-guide-to-weeds/bitter-weed Queensland Government, Department of Agriculture and Fisheries, Bitter weed ''(Helenium amarum)'']</ref>

''Helenium amarum'' is a multibranched bushy erect plant reaching 20 to 70 centimeters (8-28 inches) in height and thickly foliated in narrow to threadlike leaves. The tops of stem branches hold [[inflorescence]]s of many daisy-like [[Head (botany)|flower heads]]. Each head has a rounded center of sometimes as many as 250 golden yellow disc florets and a fringe of 8-10 usually lighter yellow [[ray florets]] which are reflexed away from the center. The fruit is a tiny [[achene]] about a millimeter long. This herb is weedy in some areas.<ref name=wwwwww>{{eFloras|1 |tribe=Heliantheae |first=Mark W. |last=Bierner}}</ref>

The plant is somewhat toxic to mammals<ref>Ivie, G. W., et al. (1975). Toxicity and milk bittering properties of tenulin, the major sesquiterpene lactone constituent of ''Helenium amarum'' (bitter sneezeweed). ''J Agric Food Chem'' 23:5 845-9.</ref> and insects<ref>Arnason, J. T., et al. (1987). Mode of action of the sesquiterpene lactone, tenulin, from ''Helenium amarum'' against herbivorous insects. ''J Nat Prod'' 50:4 690-5.</ref> due to the presence of the [[lactone]] [[tenulin]].

; Varieties<ref name=wwww/><ref name=wwwwww/>
* ''Helenium amarum'' var. ''amarum'' - United States
* ''Helenium amarum'' var. ''badium'' Waterf. - [[Oklahoma]], [[Texas]], [[Chihuahua (state)|Chihuahua]], [[Coahuila]]

==References==
{{Reflist}}

==External links==
* [http://ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?609,1294,1295 Jepson Manual Treatment]
* [https://plants.usda.gov/java/profile?symbol=HEAM United States Department of Agriculture Plants Profile]
* [http://calphotos.berkeley.edu/cgi/img_query?query_src=photos_index&where-taxon=Helenium+amarum Calphotos Photo gallery, University of California]
* [http://www.tropicos.org/ImageFullView.aspx?imageid=100402743 Photo of herbaruim specimen at Missouri Botanical Garden, collected in Mississippi in 2007]
* [http://www.illinoiswildflowers.info/prairie/plantx/bitterweed.html Illinois Wildflowers]
* {{Go Botany |genus=Helenium |species=amarum |link=1}}
* [http://www.discoverlife.org/20/q?search=Helenium+amarum Discover Life]

{{Taxonbar|from=Q5703935}}

[[Category:Plants described in 1817]]
[[Category:Flora of Northern America]]
[[Category:Helenium|amarum]]

{{Helenieae-stub}}

Helenium amarum - Revision history

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