■Genus 91.] 



THISTLE FAMILY. 



471 



91. 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 i or 2 series, narrow, 

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

 rays spreading, entire, or 2-3-toothed. Disk-flowers perfect, fertile, the corolla 5-lobed, 

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

 Achenes linear, 5-10-ribbed, more or less pubescent. Pappus a single scries of rough or bar- 

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



.\bout 20 species, natives of the northern hemisphere. Besides the following, some n others 

 occur in the western parts of North .Vmerica. 



Basal leaves ovate or oval, sessile; southern. 

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

 Basal leaves cordate-ovate. 



Basal leaves not cordate, tapering to the petiole. 

 Stem-leaves 3-5 pairs; upper somewhat smaller. 

 Stem-leaves 1-3 pairs; upper much smaller. 



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

 Leopard's-bane. (Fig. 4024.) 



Uoronicum acaiile Walt. Fl. Car. 205. 1788. 

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

 Arnica midicaiilis Nutt. Gen. 2: 164. 181S. 

 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, ob- 

 tuse, narrowed to a sessile base, denticulate 

 or entire, 2 '-5' long, ij-^ '-3' wide; stem-leaves 

 1-3 pairs, and some alternate, verysmall ones 

 above; heads I'-i^^' broad; bracts of the in- 

 volucre linear-lanceolate, acute or acutish; 

 rays 12-15, commonly 3-toothed at the trun- 

 cate apex; achenes pubescent when young, 

 glabrous or nearly so when mature. 



In low woods, Delaware and southern Penn- 

 sylvania to Florida. .\pril-May. 



1. A. acaulis. 



2. A. cordifolia. 



3. A. Chamissonis. 



4. A. alpina. 



2. Arnica cordifolia Hook. 

 Heart-leaf Arnica. (Fig. 4025.) 



Arnica cordifolia Hook. Fl. Bor. Am. i: 

 331- 1833- 



Hirsute, or pubescent; stem simple, or 

 sparingly branched, i°-2° high. Basal 

 and lower leaves ovate to nearly orbicular, 

 obtuse or acute, deeply cordate at the base, 

 dentate, I'-j' long, with slender some- 

 times margined petioles; stem-leaves 1-3 

 pairs, ovate to oblong, sessile or short-peti- 

 oled, much smaller; heads i~8,2'-3' broad; 

 bracts of the involucre acute or acuminate, 

 6"-io" long; rays 12-16, toothed at the 

 apex; achenes hirsute-pubescent, or gla- 

 brous at the base. 



Western Nebraska to the Northwest Terri- 

 tory, west to Nevada and British Columbia. 

 May-July. 



