WOOTON AND STANDLEY—FLORA OF NEW MEXICO. 735 
KEY TO THE SPECIES. 
Annuals or biennials. 
Divisions of the leaves lanceolate or linear, incised or pin- 
. biennis. 
. caudata. 
Bp 
Es 
=F 
Eh 
Q 
— 
pe pa 
Perennials. 
Heads homogamous, i. e., all the flowers fertile. 
All the leaves entire, linear to narrowly oblong....... 3. A. cana. 
Most, or at least part, of the leaves 3-toothed at the apex. 
Bracts of the involucre nearly glabrous, resinous; 
inflorescence lax, racemose................ 4. A. nova. 
Bracts tomentose; inflorescence not racemose. 
Heads campanulate, recurved.............. 5. A. petrophila. 
Heads turbinate, erect. 
Tall shrub; inflorescence much branched. 6. A. tridentata. 
Low shrub, 40 cm. high or less; inflores- 
cence rather simple and spikelike.. 7. A. arbuscula. 
Heads heterogamous, i. e., the flowers unlike, the marginal 
ones pistillate, the central ones perfect though 
sometimes sterile by the abortion of the pistil. 
Central flowers sterile, the style mostly entire and the 
ovary abortive. 
Plants shrubby, white-tomentose...............- 8. A. filifolia. 
Plants herbaceous except at the very base, green- 
ish, though sometimes pubescent. 
Upper ‘leaves all linear, only the basal ones 
pinnatifid; plants pubescent or glabrous. 
Plants glabrous throughout. ,..-....--..- 9. A. dracunculoides. 
Plants sparingly villous on stems and 
leaves......-------------+-e eee 10. A. dracunculina. 
All the leaves pinnatifid; plants somewhat 
pubescent. 
Stems tall, 50 to 100 cm. high, very leafy, 
in age nearly glabrous; divisions of 
the leaves linear-filiform; pubes- 
cence scanty......--------------Ll. A. scouleriana. 
Stems lower, 20 to 60 cm. high: divisions 
of the basal leaves linear-oblanceo- 
late, more or less canescently vil- 
lous... 2.2.2... e eee eee eee eee 12. A. forwoodii. 
Central flowers fertile; style 2-cleft. 
Receptacle densely woolly with long hairs. 
Heads large, 6 to 12 mm. in diameter; bracts 
with dark brown or blackish margins; 
plants low, 10 to 20 cm. high; spikes 
scapose; of alpine meadows..........-- 13. A. scopulorum. 
Heads small, 4 to 5 mm. in diameter; bracts 
light brown; plants taller, 30 to 60 cm. 
high; inflorescence paniculate; of the 
low plains.............--------------- 14. A. frigida. 
Receptacle not woolly, mostly smooth. 
Shrub, 30 cm. high or less; leaves cuneate, 
tridentate, silky-villous. ........--.--- 15. A. bigelovii. 
