COMPOSITAE (COMPOSITE FAMILY) 519 



toothed or lacerate. Ray-flowers numerous, violet to red or purple, pistillate; 

 disk-flowers perfect, the corollas tubular, 5-lobed, yellow, changing to red 

 or brown; anthers exserted, appendaged at the tip, rounded at the base; 

 style-appendages subulate to lanceolate. Achenes turbinate, narrowed be- 

 low, pubescent. Pappus of numerous stiff, rough, unequal bristles. Aster 

 in part. 



Annuals. 



Leaves bipinnatifid, pale green; stems usually simple below . . 1. M. tanacetifolia. 

 Leaves pinnatifid, dark green; stems branching throughout . 2. M. coronopifolia. 



Biennials or rarely perennials. 



Involucral bracts for the most part recurved or reflexed. 



Stems hirsute or hispid throughout, glandular-viscid at least 



above .......... 3. M. aspera. 



Stems glabrate or puberulent, not hispid. 



Densely glandular-viscid on the branchlets and involucre. 



Involucral bracts very viscid . . . . . 4. M. varians. 



Involucral bracts hispid as well as glandular . . 5. M. Pattersonii. 



Moderately glandular-viscid on the involucre but obscurely or 



not at all on the branchlets. 

 Stem leaves mostly spatulate-oblanceolate, 3-nerved. 



Involucral bracts lance-linear, the tips sharply deflexed 6. M. latifolia. 

 Involucral bracts almost filiform, squarrose-spreading . 7. M. Bigelovii. 

 Stem leaves mostly broadly linear or oblong, 1-nerved. 



Heads large, few; stems reddish . . . . 8. M. rubricaulis. 



Heads many; stems green 9. M. viscosa. 



Involucral bracts, for the most part, erect. 



Leaves and' stems canescently puberulent (rarely nearly gla- 

 brous). 

 Involucres obscurely or not at all glandular. 



Stems generally simple below and paniculately branched 



above ... . . . . . . . 10. M. canescens. 



Stems low, branched from the base . . . . . 11. M. shastensis. 



Involucres evidently glandular. 



Fastigiately branched from the base, with suberect stems 12. M. pulverulenta. 

 Divaricately branched throughout, with widely spreading 



stems ......... 13. M. ramosa. 



Leaves and stems glabrate 14. M. glabella. 



1. Machaeranthera tanacetifolia Nees. Ast. 224. 1832. Pubescent, often 

 rather viscid, very leafy, commonly 2-5 dm. high: lowest leaves 2-3-pinnately 

 parted; uppermost simply pinnatifid or on the flowering branchlets entire; 

 lobes short, setulose-mucronate : heads 12 mm. high; bracts of the involucre 

 narrowly linear, with slender, mostly linear-subulate, spreading, foliaceous tips, 

 or the outermost almost wholly foliaceous: rays numerous, bright violet: 

 achenes rather broad, villous. Southern Colorado to Texas and Arizona. 



2. Machaeranthera cpronopifolia (Nutt.) A. Nels. Bot. Gaz. 37: 268. 1904. 

 Annual, or possibly biennial, divaricate-branched from the base upward, 

 1-2 dm. high, green but puberulent and minutely glandular: leaves moder- 

 ately to very deeply pinnatifid, oblanceolate in outline, 1-4 cm. long; the seg- 

 ments very variable, linear to oblong or merely with broad teeth upon the 

 margins of the blade, setulose-mucronate: heads large; the involucral bracts 

 in about 5 series, the slender, green, reflexed portion of the bract about as 

 long as the scarious-imbricated base: rays often nearly 2 cm. long, bluish- 

 purple: achenes sparingly appressed-pubescent. Aster tanacetifolius in part. 

 Wyoming to Nebraska and Northern Colorado. 



3. Machaeranthera aspera Greene, Pitt. 3: 62. 1896. Biennial, stoutish, 

 freely branching, 5-8 dm. high, rough throughout, with a gland-tipped in- 

 dument which is short and scabrous on the leaves, longer and hispidulous on 

 the stem and branches : cauline leaves oblong-lanceolate, sessile by a broad, 

 half-clasping base, spinulosely serrate-toothed: heads large, somewhat race- 

 mosely disposed at the ends " of the branches; involucres hemispherical; the 

 bracts with long lanceolate spreading herbaceous tips, these glandular- 

 scabrous: achenes compressed, cuneate-oblong, striate, strigose-pubescent. 

 (M. Fremontii Rydb. Bull. Torr. Bot. Club 32: 123. 1905; M. cichoriacea 

 Greene, Leaflets 1: 148. 1905.) Frequent -at middle elevations; central Col- 

 orado. 



4. IVlachaeranthera varians Greene, Pitt. 4: 98. 1899. Biennial or short- 



