Hoary arnica, also called water arnica, is a variety of leafy arnica 

 (A. foUosa). Both the species and its variety wcana are leafy- 

 stemmed (the specific name, foliosa^ means leafy) perennials, 8 to 

 24 inches high, growing from long-running rootstocks. 



Hoary arnica occurs mostly in wet flats or meadows and often 

 grows in the shallow waters of lakes or in the beds of former pools. 

 In extremely wet places it makes a rank growth, sometimes reaching 

 21/2 feet high, and the stems become thick and hollow. Hoary arnica 

 is probably most common in California, where it often grows in 

 abundance in mountain meadows. It is also occasionally found in 

 drier situations, such as sagebrush- weed types. It ranges northward 

 .from California to Washington and eastward to Montana and Colo- 

 rado. Leafy arnica (the species) grows in moist situations in 

 canyon bottoms, open meadows, and parks, and under scattered 

 timber at moderate to high elevations from Alaska to northern New 

 Mexico and Utah. 



Neither the variety nor the species is of any particular value for 

 iforage, although sheep sometimes graze leafy arnica lightly, at least 

 the flower heads. Hoary arnica often grows in places wetter than 

 sheep care to enter. Moreover, in most places its palatability is low 

 or worthless but, in the absence of better feed, it may sometimes 

 be grazed moderately by sheep or even cattle. Deer are said to eat it 

 when it is dry. Occasionally, California stockmen report this plant 

 as poisonous to livestock, especially cattle, because of losses suffered 

 from grazing areas surrounding alkali ponds and pools. It should 

 be understood, however, that there is no reliable substantiating evi- 

 dence in support of this belief. 



Both hoary arnica and leafy arnica are variable as to leaf shape, 

 and the kind and amount of hairiness, and they also intergrade more 

 or less with each other. Perhaps this variability explains why these 

 plants have been so variously described and named in the different 

 manuals. Hoary arnica appears in western botanical literature 

 under at least four different names, Arnica ca/na,, A. demudatcu ca- 

 nesceiis, A. foliosainccma, and A. inccma (A. Gray) Greene (N. B. 

 The older A. incasna Pursh refers to a different plant) . Leafy arnica 

 appears in western botanical manuals under at least seven different 

 names, A. celsa, A. chamissonis in part, A, demwdata-, A. foliosa, A. 

 oereata, A. rhizomata, and A. tom^ntvilosa. The stems of hoary 

 arnica are usually more densely haired and white-woolly than are 

 those of leafy arnica. Hoary arnica grows partly submerged in 

 water more often than does leafy arnica, and when growing thus 

 the lower part of the stem becomes free from hair (glabrate) and 

 both the underground rootstocks and the lower part of the stem 

 become hollow inside, perhaps to admit air to the submerged parts. 



