¥4 Arnica L. 
Perennial herbs with creeping, often elongate rootstocks, the basal 
leaves usually differing from the cauline, the latter diminished upwards, 
opposite, the lower pairs resembling the basal leaves, being thus either 
cordate or narrowed at the base, the uppermost pairs sessile. Heads 
solitary or several, the involucres top-shaped or hemispherical, their 
bracts thin and membranous, in 1 or 2 series, erect. Receptacle flat or convex, 
naked or pubescent. Ray-flowers pistillate and fertile, the rays conspicuous, 
yellow; disc-flowers numerous, their tubes pubescent. Achenes columnar, rarely 
glabrous, mostly either hispidulous or sprinkled with short glandular hairs. 
Pappus a single series of scabrous bristles. 
© Lower loaves oblanceolate or obovate, narrowed toward the 
4 base 
Z Achenes sprinkled with minute glands or resin dots, 
% sometimes with scattering short hairs 
“4/ Stem and leaves glabrate, glandular puberulent, 
CT ns latter Linear-lanceolate,seldom more 
than 1.5 cm. wide : |, As longifolia 
/{ Stem and leaves short-woolly, the latter 1.5=2.5 CM « 
e @ wide, oblong-lanceolate or oblong : 
: @ Involucral bracts 1.5-3 mm. wide, 10-12 . 
/o mm. long 2, A- mollis 
qd © Involucral bracts 1-2 mm. wide, 6-8 mn. long 3. A. Chamissonis q 
2 Achenes hispidulous or hirsute, or glabrous, not 
»at all glandular 
4 Achenes glabrous % A. crassa 
6 Achenes hispidulous or hirsute 
(> Ray-corollas orange; achenes softly hirsute, 
so plants 10-20 cm. tall S° A. Rydbergii 
_ } 
} Ray-corollas yellow; achenes hispidulous, i 
jo Plants 30-50 cm. tall, rarely less i 
1 
; 
S Leaves entire or nearly so; heads i 
/é solitary G. Ae pedunculata i 
* Leaves sharply toothed, heads several, : 
jz rarely solitary 7. As Macounii 
a 
© Basal leaves and often the lower stem leaves cordate i 
4 or reniform 
Achenes glabrous a. Ae latifolia 
q) *% Achenes hispidulous 
Gracts of involucre]' 
: S-12 mne long, ray=corollas 
= 12-20 mm. long ; 
