254 ASTER FAMILY 



1. Plants with stolons, forming mats 



a. Heads in a dense head-like cluster 



(1) Involucres brown, greenish-brown or 



brownish A. alpina 



(2) Involucres white or pink, greenish at base 



(a) Involucres 4-6 mm. high 



x. Basal leaves obovate to spatulate, dense- 

 ly silvery-white, 1-1.5 cm. long A. dioeca 



y. Basal leaves narrowly lanceolate or ob- 

 lanceolate, greenish-silvery, 2-3 cm. 

 long A. corymb osa 



(b) Involucres 7-10 mm. high; leaves spatu- 



late to obovate A. dprica 



b. Heads in an open raceme-like cluster A. racemosa 



2. Plants in tufts, or single, without stolons 



a. Heads solitary; stems tufted, 1-2 in. high; 



leaves spatulate, 1-3 cm. long A. dimorpha 



b. Heads in a corymb-like or head-like cluster; 



stems .5-2 ft. high; leaves linear to lanceo- 

 late or oblanceolate, 2-10 cm. long A. carpdthica 



Anthemis Linne 1753 Mayweed 

 (Gr. anthemis, flower) 



Heads with white, neutral or pistillate ray-flowers, disk-flowers yel- 

 low, perfect, achenes oblong, 10-angled, 10-ribbed, roughened, pappus 

 none or a short border; receptacle convex to oblong, with chaff, involucre 

 hemispheric, bracts with papery margins, imbricated in several series; 

 heads at the ends of the branches ; leaves alternate, pinnatifid or dis- 

 sected, strong-scented ; annual or perennial. 

 Stems .5-2 ft. high; leaves finely dissected A. cotula 



Arnica Linne 1753 Arnica 



(Origin and meaning uncertain) 



PI. 40, fig. 2. 



Heads with yellow ray-flowers, the latter sometimes wanting, ray- 

 flowers pistillate entire, or 2-3-toothed, disk-flowers yellow, perfect, achenes 

 linear, 5-10-ribbed, pappus a single row of barbed, hair-like bristles; re- 

 ceptacle flat without chaff, involucre bell-shaped or top-shaped, bracts nearly 

 equal in 1-2 series; heads solitary or few in a corymb; leaves mostly oppo- 

 site, simple, entire or toothed ; perennial. 



