WOOTON AND STANDLEY FLOEA OF NEW MEXICO. 



687 



1. Leucosyris spinosus (Benth.) Greene, Pittonia 3: 244. 1897. 



Aster spinosus Benth. PL Hartw. 20. 1839. 



Type locality: Mexico. 



Range: Utah and California to Texas and New Mexico and southward. 



New Mexico: Albuquerque; Socorro; Cliff; near WTiite Water; Mesilla Valley; 

 San Antonio. In heavy, usually adobe soil, in the Lower Sonoran Zone. 



39. MACHAERANTHERA Nees. 



Stout, rather coarse annuals or biennials with slender or thick taproots; stems 

 usually much branched; leaves alternate, from simple and dentate to bipinnately 

 parted into linear segments; heads rather large, camijanulate, terminating the 

 branches, with purple rays; involucre much imbricated, the bracts linear, coriaceous 

 below, with foliaceous, often spreading tips; achenes narrowed downward, com- 

 pressed, few-nerved, pubescent or glabrous; pappus copious, of rather rigid unequal 

 bristles. 



KEY' TO THE SPECIES. 



Annuals; leaves pinnatifid; achenes mostly terete. 



Leaf segments acute, usually bristle-tipped; heads large; 

 plants abundantly pubescent. 

 Heads large, 12 to 15 mm. in diameter; bracts narrow, 

 subulate-tipped; plants si^reading, large, 30 cm. 



high or more 1. M. tanaceti/olia. 



Heads about 10 mm. in diameter; bracts broad, not 

 subulate-tipped; plants erect, small, usually 



less than 20 cm. high 2. 3f. tagetina. 



Leaf segments obtuse, not bristle-tipped; heads small; 

 plants sparingly pubescent. 

 Leaves densely glandular; many of the leaves twice 



pinnatifid, the segments broad 3. M. pygmaea. 



Leaves not glandular; leaves once pinnatifid, the seg- 

 ments narrow 4. 31. parviflora. 



Biennials, sometimes perennials; leaves merely toothed or en- 

 tire; achenes compressed. 

 Tips of the bracts short, lanceolate or rhombic, usually 

 little reflexed. 

 Heads small, less than 10 mm. broad; leaves thick, 

 siDaringly toothed, little if at all ciliate; pe- 

 duncles very leafy 5. 31. cichoriacea. 



Heads 12 mm. broad (y- more; leaves thin, salient- 

 toothed, ciliate; peduncles sparingly leafy 6.. 31. linearis. 



Tips of the bracts long, linear or subulate, reflexed. 

 Plants nowhere glandular. 



Stems stout, much branched; leaves thick, lanceo- 

 late or oblong 7. 3f. asteroides. 



Stems slender, simple or nearly so; leaves thin, 



oblanceolate 8. M. simplex. 



Plants glandular, at least on the bracts. 



Plants densely and coarsely glandular almost 

 throughout. 

 Cauline leaves narrow, mostly 1-veined; 



leaves stiff, rigid 9. 31. viscosa. 



Cauline leaves broader, triple- veined; leaves 

 thinner. 



