210 GENUS CHRYSOTHAMNUS, 



Artificial Key to the Subspecies of Chrysothamnus nauseosus.^ 



Involucres puberulent (at least the short outer bracts) or tomentulose to densely woolly; 

 fohage mostly gray or even white with a rather copious pubescence 

 (least pronounced in speciosus and sometimes yellowish-green in 

 turhinatus, bigelovi, and glareosus). 

 Achenes densely pubescent. 



Tomentum loose, copious, and nearly pure white on twigs and leaves, extending to 

 the involucres; corolla-tube often arachnoid-pubescent. 

 Inner bracts of involucre plainly tomentose or if nearly glabrous the bracts then 

 acute. 

 Corolla-lobes lanceolate, 1 to 2 mm. long; style-appendage longer than the 



stigmatic part (e) albicaulis (p. 212). 



Corolla-lobes short-ovate, less than 1 mm. long; style-appendage shorter than 



the stigmatic part (6) hololeucus (p. 211). 



Inner bracts smooth and glabrous or nearly so, very obtuse (d) latisquameus (p. 212). 



Tomentum close, compact, smooth, and gray or white on twigs, the leaves gray or 

 greenish and sometimes nearly glabrous; corolla-tube glabrous or 

 puberulent, only rarely arachnoid-pubescent. 

 Bracts gradually acute or somewhat obtuse. 

 Involucre 6 to 9 or rarely 10 mm. high.' 



Shrubs only 2 to 6 dm. high; corolla 6.5 to 8 mm. long' (very rarely 9 mm.) . . (J) typicus (p. 213). 



Shrubs normally 4 to 20 dm. high; corolla 8 to 10 mm. long or rarely only 



7 mm. in gnaphalodes^ (latisquameus of Arizona and New Mexico, 



with broad and very obtuse and smooth inner bracts, might be 



sought here). 



Corolla-lobes 1 to 2 mm. long; style-appendage longer than stigmatic portion. 



Leaves 1 to 3 mm. wide, 1-nerved; bracts various but mostly acute (c) speciosus (p. 211). 



Leaves 3 to 5 mm. wide, 3-nerved; bracts mostly obtuse (g) salieifolius (p. 213). 



Corolla-lobes 0.5 to 1 mm. long; style-appendage shorter than stigmatic 



portion (a) gnaphalodes (p. 211). 



Involucre 11 to 12 mm. or rarely only 10 mm. high.' (Involucres of turbinatus, 

 if shorter, may be known by their oylindric shape.) 



Corolla-lobes about 0.5 mm. long, villous (q) turbinat'us (p. 217). 



Corolla-lobes nearly 2.0 mm. long, glabrous (i) bernardimis (p. 214). 



Bracts abruptly acute. Far western (h) occidentalis (p. 213). 



Achenes glabrous. 



Bracts of the involucre obtuse; corolla 10 to 12 mm. long (r) glareosus (p. 217). 



Bracts of the involucre very acute; corolla 9 to 10 mm. long (s) bigelovi (p. 217). 



Involucres perfectly glabrous, although sometimes viscidulous or glandular; foliage mostly 

 greenish, the tomentum rather sparse or wanting on mature leaves. 



Achenes glabrous or nearly so (t) leiospermus (p. 217). 



Achenes densely pubescent. 



Leaves linear, mostly more than 1 mm. wide,' mostly 1- to 5-nerved. 



Involucre 10 mm. or more long; corolla 9 to 12 mm. long; lobes 1.5 to 2.5 mm. long. 



Southern California (t) bernardinus (p. 214). 



Involucre 6 to 8 mm. long, corolla 7 to 9 mm. long; lobes 0.5 to 1.5 mm. long (j) graveolens (p. 214). 



Leaves linear-filiform or very narrowly linear, mostly 1 mm. or less wide (except in 

 occidentalis), 1-nerved. 

 Bracts of the involucre obtuse to acute, not abruptly pointed. 



Corolla -lobes glabrous; shrub leafy except sometimes in mohavensis. 



Involucre 7 to 9 mm. long, not sharply angled, the bracts moderately keeled, 

 5-rowed. 

 Corolla 7 to 9 mm. long; lobes under 2 mm.; twigs and foliage slender. 

 Lobes of corolla 0.5 to 1 mm. long, rarely more; inflorescence typically 



rounded to pyramidal. Rocky Mountain States (k) pinifolius (p. 215). 



Lobes of corolla 1 to 2 mm. long, inflorescence typically oylindric to pyram- 

 idal. Great Basin (I) consimilis (p. 215). 



Corolla 7 to 10 mm. long; lobes 1.7 to 2.5 mm. long; twigs and fohage 



stouter. Southwestern (m) viridulus (p. 215). 



Involucre 9 to 10 mm. long, sharply 5-angled, the strongly keeled bracts in 



very distinct vertical rows (o) mohavensis (p. 216). 



Corolla-lobes sparsely long-hairy in the bud; shrub nearly leafless (p) junceus (p. 216). 



Bracts of the involucre abruptly pointed or some only acute. Far western. 



Tip of the bract short, erect {h) occidentalis (p. 213). 



Tip of the bract about 1 mm. long, very slender, recurved (n) ceruminosus (p. 216) . 



' A natural key has not been prepared, but the groupings according to a natural system are given in figure 28, page 223. 

 ' These measurements are of fully mature involucres and corollas, the latter either fresh or restored by boiling. 

 • Care must be exercised in making this measurement since the leaves are often longitudinally folded. The figures given 

 are for the total width of the flat leaf. 



