W22 



ARNICAS 



Ar'nica spp. 



Arnica is a genus of perennial herbs of the composite (aster .or 

 sunflower) family, represented in the West by about 37 species. 

 The arnicas occur throughout the mountains of the Western States, 

 being much less common in the Southwest than in other sections. 

 They occupy a wide variety of sites ; some species are fairly drought- 

 resistant while others grow best in wet or marshy areas. Taken as 

 a whole, the favorite habitat of plants of this genus is moist shady 

 woodlands or coniferous timber stands at moderate to high eleva- 

 tions. 



In general, the arnicas are considered unimportant as forage 

 plants, though their forage value is a matter for local determina- 

 tion, as it varies greatly with the species, the locality, and the pres- 

 ence and abundance of more palatable associates. Most arnicas are 

 worthless or low, and, at best, only fair in palatability. Some spe- 

 cies, however, are regarded locally as being moderately to highly 

 palatable, especially for sheep. The flower heads are the portion 

 of the plant most readily eaten. 



The generic name Arnica appears to have been invented by the 

 great Swedish botanist, Linnaeus (1707-78), possibly as a corrup- 

 tion of the old plant name Ptarmica. The medicinal arnica of com- 

 merce, which is used popularly in the treatment of bruises, sprains, 

 rheumatic pains, and other ailments, is obtained from the flower 

 heads and rootstocks of the European species, Arnica montana. It 

 is with this medicinal product that the word arnica is most famil- 

 iarly associated. Because of the similarity in appearance, odor, and 

 taste, close botanical relationship, and use by the Indians, there is 

 reason for believing that some of our native western arnicas may 

 possess medicinal properties similar to those of the European species. 



One of the most outstanding things about the plants of this genus 

 is the typical opposite (paired) arrangement of the leaves although 

 rarely the upper leaves are alternate. The erect stems are 6 inches 

 to 2 feet high. One or more large sunflowerlike flower heads with 

 showy yellow petal-like parts (ray flowers) are borne at the sum- 

 mit of the stems. Several species, of which rayless arnica, often 

 called Parry arnica (A. parryi), is the most common, have no petals 

 (ray flowers). The center, or disk portion of the flower head, is 

 made up of numerous small ? tubular flowers set upon a common, 

 smooth (not chaffy but sometimes hairy) flattened base (receptacle). 

 The involucre (circle of bracts around the flower head) is composed 

 of oblong-lance-shaped to linear bracts (phyllaries). The seedlike 

 fruits (achenes) are slender, somewhat spindle-shaped, and crowned 

 with a circle or tuft of numerous, rigid, white, or grayish-tawny 

 hairs. 



