Helenium amarum
Helenium amarum is a species of annual herb in the 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)[4] and northern Mexico (Chihuahua, Coahuila),[5] and it is present elsewhere in North America, Australia, and the West Indies as an introduced species.[4][6][7][8]
| Helenium amarum | |
|---|---|
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| Scientific classification  | |
| Kingdom: | Plantae | 
| Clade: | Tracheophytes | 
| Clade: | Angiosperms | 
| Clade: | Eudicots | 
| Clade: | Asterids | 
| Order: | Asterales | 
| Family: | Asteraceae | 
| Genus: | Helenium | 
| Species: | H. amarum  | 
| Binomial name | |
| Helenium amarum (Raf.) H.Rock  | |
| Synonyms[2][3] | |
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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 inflorescences of many daisy-like 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.[5]
The plant is somewhat toxic to mammals[9] and insects[10] due to the presence of the lactone tenulin.
References
    
- "NatureServe Explorer 2.0". explorer.natureserve.org.
 -  "Helenium amarum". The Plant List. Missouri Botanical Garden. Royal Botanic Gardens, Kew.
{{cite web}}: CS1 maint: others (link) Note that this website has been superseded by World Flora Online - "Gaillardia amara". Tropicos. Missouri Botanical Garden.
 - "Helenium amarum". County-level distribution map from the North American Plant Atlas (NAPA). Biota of North America Program (BONAP). 2014.
 - Bierner, Mark W. (2006). "Helenium amarum". In Flora of North America Editorial Committee (ed.). Flora of North America North of Mexico (FNA). Vol. 21. New York and Oxford: Oxford University Press – via eFloras.org, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
 - Turner, B. L. 2013. The comps of Mexico. A systematic account of the family Asteraceae (chapter 11: tribe Helenieae). Phytologia Memoirs 16: 1–100.
 - Tropicos, specimen listing for Helenium amarum (Raf.) H. Rock
 - Queensland Government, Department of Agriculture and Fisheries, Bitter weed (Helenium amarum)
 - 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.
 - 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.
 
External links
    
- Jepson Manual Treatment
 - United States Department of Agriculture Plants Profile
 - Calphotos Photo gallery, University of California
 - Photo of herbaruim specimen at Missouri Botanical Garden, collected in Mississippi in 2007
 - Illinois Wildflowers
 - Go Botany, New England Wildflower Society
 - Discover Life
 

