Genus 97. 



THISTLE FAMILY. 



533 



97. ARNICA L. Sp. PI. 884. 1753. 

 Erect, simple or little branched herbs, with opposite leaves, or the upper rarely alternate, 

 and large, long-peduncled heads of both tubular and radiate, yellow flowers, or rays wanting 

 in some species. Involucre turbinate or campanulate, its bracts in 1 or 2 series, narrow, 

 nearly equal. Receptacle flat, naked, fimbrillate or villous. Ray-flowers pistillate, fertile, the 

 rays spreading, entire, or 2-3-toothed. Disk-flowers perfect, fertile, the corolla S-lobed, the 

 style with slender branches. Anthers entire or minutely 2-auriculate at the base. Achenes 

 linear, 5-10-ribbed, more or less pubescent. Pappus a single series of rough or barbellate,. 

 rigid, slender bristles. [Derivation uncertain, perhaps from Ptarmica.] 



About 45 species, natives of the northern hemisphere. Besides the following, many others, 

 occur in the western parts of North America. Type species : Arnica montana L. 

 Basal leaves ovate or oval, sessile; southern. i. A. acaulis. 



Basal leaves oblong, lanceolate, or cordate-ovate, petioled. 



Basal leaves cordate-ovate. 2. A. cordifolia. 



Basal leaves not cordate, tapering to the petiole. 

 Leaves dentate. 



Pappus brownish, plumose. 3. 



Pappus white, barbellate. 

 Leaves entire or nearly so. 



A. mollis. 



4. A. chionopappa. 



5. A. alpina. 



i. Arnica acaulis (Walt.) B.S.P. 

 Leopard's-bane. Fig. 4599. 



Doronicum acaule Walt. Fl. Car. 205. 17S8. 

 Arnica Claytoni Pursh, Fl. Am. Sept. 527. 1814. 

 Arnica nudicaulis Nutt. Gen. 2: 164. 1818. 

 Arnica acaulis B.S.P. Prel. Cat. N. Y. 30. 1888. 



Glandular-hirsute; stem i-3 high, bearing 

 several slender-peduncled heads at the sum- 

 mit. Basal leaves tufted, ovate or oval, obtuse, 

 narrowed to a sessile base, denticulate or en- 

 tire, 2'-5' long, i*'-3' wide; stem leaves 1-3 

 pairs, and some alternate, very small ones 

 above; heads l'-li' broad; bracts of the invo- 

 lucre linear-lanceolate, acute or acutish ; rays 

 12-15, commonly 3-toothed at the truncate 

 apex ; achenes pubescent when young, glabrous 

 or nearly so when mature. 



In low woods, Delaware and southern Pennsyl- 

 vania to Florida. April-May. 



2. Arnica cordifolia Hook. Heart- 

 leaf Arnica. Fig. 4600. 



Arnica cordifolia Hook. Fl. Bor. Am. 1: 331. 

 1833- 



Villous or pubescent ; stem simple or 

 sparingly branched, glandular above, l-2 

 high. Basal and lower leaves ovate to 

 nearly orbicular, obtuse or acute, deeply 

 cordate at the base, dentate, l'-f long, 

 with slender sometimes margined petioles ; 

 stem leaves 1-3 pairs, ovate to oblong, ses- 

 sile or short-petioled, much smaller; heads 

 1-8, 2-3' broad ; bracts of the involucre 

 acute or acuminate, villous, 6"-io" long; 

 rays 12-16, toothed at the apex ; achenes 

 hirsute-pubescent, or glabrous at the base; 

 pappus barbellate, white. 



Lake Superior to North Dakota, Yukon. 

 Montana, New Mexico and California. Re- 

 corded from western Nebraska. May-July. 



