1000 MISC. PUBLICATION 4 2 3, U. S. DEPT. OF AGRICULTURE 



Key to the species 



1. Plants shrubs or undershrubs, with foliage silvery-canescent on both sides (2). 



2. Leaves twice or thrice pinnatifid into linear divisions; receptacle villous; 



plant an undershrub, 20 to 50 cm. high, several- or many-stemmed. 



8. A. FRIGIDA. 

 2. Leaves entire, 3-toothed, or 3-parted; receptacle glabrous; plants often 

 taller (3). 

 3. Leaves linear-filiform, less than 1 mm. wide, entire or 3-parted. 



11. A. FILIFOLIA. 

 3. Leaves broader, at least the lower ones 3-dentate at apex (4) . 



4. Pistillate outer flowers (1 or 2) usually present; involucre densely and 

 persistently gray-tomentose throughout, only about 2 mm/high. 



7. A. BIGELOVII. 



4. Pistillate outer flowers none; involucre usually glabrate, at least on 

 the inner phyllaries, larger (5). 

 5. Heads very numerous, in dense crowded panicles 1.5 to 7 cm. thick; 

 phyllaries, at least the outer ones, canescent-pubescent; plants 



usually at least 50 cm. high 12. A. tridentata. 



5. Heads fewer, in less crowded often spikelike or racemelike panicles 

 rarely more than 1.5 cm. thick; phyllaries greenish yellow or 

 yellowish brown, nearly glabrous; plants 10 to 30 cm. high. 



13. A. NOVA. 

 1. Plants herbs or, if rarely shrubby, then the foliage not silvery-canescent, al- 

 though often white-tomentose (6) . 

 6. Branchlets spinescent; achenes of the pistillate flowers cobwebby-pubescent; 

 leaves small, about 1 cm. long, roundish in outline, twice to thrice 



pinnatifid into spatulate divisions 14. A. spinescens. 



6. Branchlets not spinescent; achenes glabrous or merely glandular (7). 

 7. Leaves, at least the lower ones, twice or thrice pinnatifid (8). 

 8. Plant essentially glabrous, equably leafy throughout; leaves twice or 

 thrice pinnatisect into very numerous acute divisions (9). 

 9. Panicle dense, spikelike; plant inodorous 5. A. biennis. 



9. Panicle very loose and broad; plant sweet-scented. _ 6. A. annua. 

 8. Plant decidedly hairy, at least on the lower leaves or the under leaf 



surface, the leaves usually much reduced above (10). 



10. Whole plant densely silky-canescent; receptacle villous. 



8. A. FRIGIDA. 

 10. Plant not silky-canescent except sometimes on the lower leaves; 

 receptacle glabrous (11). 

 11. Leaves green above, canescent- tomentulose beneath, bipinnatifid, 

 the divisions not linear-filiform; heads 5 to 7 mm. thick. 



1. A. FRANSERIOIDES. 



11. Leaves about equally pubescent on both sides, not bicolored, the 

 principal divisions linear-filiform or very narrowly linear; heads 



about 2 to 3 mm. thick 10. A. pacifica. 



7. Leaves entire to once pinnatifid (12). 



12. Leaves elongate-linear, entire or some of the lower ones sometimes 

 3-cleft, usually 5 to 8 cm. long, 1 to 6 mm. wide, glabrous or some- 

 what pubescent but never tomentose 9. A. DRACUNCULOIDES. 



12. Leaves usually broader or else usually lobed, toothed, or pinnatifid, 

 always tomentose, at least beneath (13). 

 13. Leaves pinnatisect essentially to the midrib into linear or linear- 

 filiform lobes 1 mm. wide, or narrower 4. A. carruthii. 



13. Leaves from entire to toothed or pinnatisect, the lobes when present 

 2 mm. wide, or wider (14). 

 14. Leaves oblong or oblong-lanceolate, persistently gray-tomentose 

 above, entire or few-toothed, or the lower ones sometimes with 



a few short broad lobes 2. A. gnaphalodes. 



14. Leaves linear to lanceolate or rarely oblong or obovate, soon 

 glabrate and green above, from entire to deeply pinnatifid. 



3. A. LUDOVICIANA. 



1. Artemisia franserioides Greene, Torrey Bot. Club Bui. 10 : 42. 



1883. 



Pinaleno Mountains (Graham County), Chiricahua Mountains 

 (Cochise County), Santa Catalina Mountains (Pima County), 8,000 



