WOOTON AND STANDLEY—FLORA OF NEW MEXICO. 687 
1. Leucosyris spinosus (Benth.) Greene, Pittonia 3: 244. 1897. 
Aster spinosus Benth. Pl. Hartw. 20. 1839. 
Typre LocALity: Mexico. 
RanGE: Utah and California to Texas and New Mexico and southward. 
New Mexico: Albuquerque; Socorro; Cliff; near White 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, campanulate, 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 spreading, large, 30 cm. 
high or more............ . 1. M. tanacetifolia. 
Heads about 10 mm, in diameter; “bracts ‘broad, ‘not 
subulate-tipped; plants erect, small, usually 
less than 20 cm. high...........-.------------- 2. M. 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 DaITOW....----------- 22-0 e ee eee eee 4, M. 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, 
sparingly toothed, little if at all ciliate; pe- 
duncles very leafy. .........--------------+--- 5. M. cichoriacea. 
Heads 12 mm. broad or more; leaves thin, salient- 
toothed, ciliate; peduncles sparingly leafy.....- 6. M. linearis. 
Tips of the bracts long, linear or subulate, reflexed. 
Plants nowhere glandular. 
Stems stout, much branched; leaves thick, lanceo- 
late or oblong.......-------------------5-- 7. M. asteroides. 
Stems slender, simple or nearly so; leaves thin, 
oblanceolate........--- 22-222 ..e eee cece eee 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. M. viscosa. 
Cauline leaves broader, ‘triple- -veined; "leaves 
thinner. 
