ACHILLEA AGOSERIS 251 



ACHILLEA Linne 1753 MILFOIL, YARROW 



(Named for Achilles) 



Heads with white or pink pistillate ray flowers, disk flowers yellow, 

 perfect, achenes oblong or obovate, slightly flattened, pappus none; recep- 

 tacle flat or convex, with chaff, involucre bell-shaped, the bracts imbricated 

 in several rows ; heads in flat-topped corymbs ; leaves alternate, finely dis- 

 sected ; perennial. 



Stems 1 in. to 3 ft. high; leaves finely dissected, 1-10 

 in. long; rays 4-6, white to rose A. mille folium 



ACTINELLA Nuttall 1818 



(Gr. aktis, aktinos, ray) 



(Hymenoxys Cassini) 



PI. 40, fig. 6 ; PI. 41, fig. 2. 



Heads with yellow ray flowers, rarely rayless, ray-flowers pistillate, 

 3-toothed, disk flowers perfect, yellow to brownish, achenes top-shaped, 

 5-10-ribbed or angled, usually hairy, pappus of 5-12 usually pointed scales; 

 receptacle convex to conic, without chaff, involucre bell-shaped or hemi- 

 spheric, bracts imbricated in 2-3 rows ; heads single or clustered ; leaves 

 alternate or basal, often dotted with glands ; stemmed or stemless, annual 

 or perennial. 



1. Leaves entire 



a. Stems with 1-4 leaves in addition to those at 



the base A. leptoclada 



b. Stems leafless, the leaves all basal, smooth to 



variously hairy A. acaulis 



2. Leaves ternately cut into linear lobes 



a. Perennial from a branched caudex; heads sol- 



itary to many A. Richardsonii 



b. Annual from a tap root A. multi-flora 



AGOSERIS Rafinesque 1817 



(Gr. aix, agos, goat, sens, chicory) 



(Troximon Nuttall) 



PI. 37, fig. 4. 



Heads with yellow, orange or purple strap-shaped perfect flowers, the 

 tip 5-toothed, achenes oblong to linear or obovate, 10-ribbed with a short 

 or long beak, pappus of white, hair-like bristles; receptacle flat, involucre 

 bell-shaped or oblong, the bracts imbricated in several rows ; heads solitary 

 on leafless stalks ; leaves simple to pinnatifid ; annual or perennial. 

 1. Heads yellow, the rays occasionally purplish 

 outside or when old 



