COMPOSITAE (COMPOSITE FAMILY) 499 



1-2.5 cm. long, firm, spinulose-dentate : heads terminating the stem or 

 branches; involucre campanulate, the bracts linear, acute, puberulent, the 

 tips somewhat spreading, the outer shorter than the inner: achenes densely 

 silky-tomentose. Aplopappus Nuttallii. Dry soil; from New Mexico and 

 Arizona to the Canadian border. 



4. Sideranthus australis (Greene) Rydb. Bull. Torr. Bot. Club 27: 621. 

 1900. Perennial^the clustered stems erect or ascending, 1-4 dm. high, not 

 tomentose but cinereous with a short spreading somewhat glandular indu- 

 ment: radical leaves pinnatifid, the lobes with few coarse teeth; the cauline nar- 

 row, pinnately toothed: heads few, solitary at the ends of leafy pedunculiform 

 branches: rays pale yellow: achenes compressed; pappus-bristles not coarse, 

 extremely unequal. (S. puberulus Rydb. 1. c. In this and the next species 

 there are all degrees of pubescence.) Colorado and New Mexico. 



5. Sideranthus spinulosus (Pursh) Sweet. Hort. Brit. 227. 1826. From 

 lanate or tomentose to glabrate, much branched at the base, perennial from 

 thick woody roots, 1-4 dm. high: leaves pinnatifid, linear to ovate in outline, 

 1-3.5 cm. long, the lobes with bristle-pointed teeth: heads several or nu- 

 merous, 12-25 mm. broad; involucre hemispheric, the bracts linear, acute, 

 appressed: achenes pubescent, narrowed below; pappus soft and capillary. 

 On the plains; from the base of the mountains to the Dakotas, Nebraska, and 

 Texas. 



5a. Sideranthus spinulosus glaberrimus (Rydb.) A. Nels. Wholly gla- 

 brous; not otherwise distinguishable. (S. glaberrimus Rydb. 1. c.) -Same 

 range as the species. 



12. PYRROCOMA Nutt. 



Perennial herbs with mostly simple stems, alternate leaves, and showy 

 heads of yellow flowers terminal or in the axils of the upper leaves. Heads 

 many-flowered, radiate. Bracts of the hemispherical or campanulate in- 

 volucre rigid, somewhat foliaceous, nerveless, oblong with more or less squar- 

 rose or herbaceous tips. Receptacle flat, alveolate-toothed. Ray-flowers 

 numerous, pistillate; disk-flowers cylindrical, slightly dilated upward with 

 short, erect teeth. Style-branches of the disk-flowers subulate-linear, elon- 

 gated, the hispid appendages much longer than the stigmatic portion. Achenes 

 linear, elongated, somewhat 3-angled and striate, glabrous or rarely hairy. 

 Pappus reddish-brown or fulvous, of copious and uniform, slender, rigid 

 bristles. Aplopappus in part. 



Involucral bracts with broad obtuse tips . . . . . . 1. P. crocea. 



Involucral bracts acute or acuminate. 



Heads mostly solitary, terminal, rarely 1-2 smaller ones in the upper 



axils. 

 Heads large, the disk more than 2 cm. in diameter. 



Stem and involucre villous * . . . . . . 2. P. Clementis. 



Stem and involucre glabrate 3. P. integrifolia. 



Heads smaller; the disk less than 2 cm. in diameter . . . 4. P. uniflora. 

 Heads several to many, paniculately corymbose or racemiform . 5. P. lanceolata. 



1. Pyrrocoma crocea (Gray) Greene, Erythea 2: 69. 1894. Stems stout 

 and erect, commonly 3-5 dm. high, and with radical leaves (including the 

 petiole) 1-2 dm. long: cauline leaves ovate-oblong to lanceolate, partly clasp- 

 ing: heads mostly solitary; involucre about 3 cm. in diameter; the bracts ovate 

 to spatulate-oblong, very obtuse, lax, inner with scarious, erose-denticulate 

 margins: rays saffron-yellow, sometimes 25 mm. long: achenes narrowly ob- 

 long, nearly as long as the pappus. Aplopappus crocea. In the Colorado 

 mountains. 



2. Pyrrocoma Clementis Rydb. Bull. Torr. Bot. Club 27: 625. 1900. Stems 

 1 or more, ascending, 1-2 dm. high, more or less villous as is also the in- 

 volucre: lower stem leaves linear-oblong, about 1 dm. long, glabrous except 

 the ciliate margin, saliently dentate; the upper lanceolate or ovate-lanceolate, 

 dentate or entire-margined: heads solitary; disk about 2.5 cm. broad; bracts 

 all foliaceous, imbricated in 3-4 series, but the outer almost equaling the 



