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. 



Aiinuals. 



Leaves Bipinnatifid, pale green; stems usually simple below , . IJ M. tanacetlfolia. 

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

 Biennials or rarely perennials. i 



Invobicral bracts for the niost part recurved or reflexed. 



Steins hirsute or hispid' throughout, glandular-viscid at least 



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



Stems glabrate or puberulent, not hispid. , ,^ 



Densely glandular-viscid on the brahchlets and involucre. 



Involucral bracts very viscid '.■'.■. . . . 4. M, varians. 



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

 ■ , , ' Moderately glandular-viscid on the involucre but obscurely or 

 J . n6t at all on the branchlets. ,,, 



Stem leaves mostly spatulate-oblanc'eolate, 3-nervfed. 



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

 Involupralbracts almost filiform, squarrose-spreading ■ . 7. M. Bigelovii. 

 Stein leaves mostly broadly linear or oblong, l-nerved. 

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



' ' 1 1 , ' . ■ Heads many; stems green . . . . . . ' . 9. M. viscosa. 



I i 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 branqhed 



above . . . . . . . •. ' . 10. M. caiiescens. 



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



Involucres evidently glandular. 



Fastigiately brar^ched from the base, with suberect stems 12. M. pulverulenta. 

 Divaricately branched throughout, with widely spreading 



stems . .......'.' 13. M. Tathosa. 



Leaves and stems glabrate . ', - , , ■. . . 14. M.' 'glabella. ■ 



1. Machaeranthera tanacetifoUa 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 th|0 flowering branchlets entire; 

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

 jiarrowly linear, with slender, mostly linear-subulate, spreading, f oliaceous tips, 

 or the outermost almost wholly f oliaceous; rays numerous, bright, violet: 

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



2. Machaerantheracoronopifolia (Nutt.) A. Nels. B.ot. Gaz. 37: 268. 1904. 

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

 1-2 dm. high,, green but puberulent and mimately 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 bl^de, setulose-mucronate: heads large; [the involucral bracts 

 in, about 5 series,:. thciSlender, green, reflexed portion of the bract, about as 

 long as I the scarious-imbricated base: rays often nearly 2,cni, Ipng, bluish- 

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

 Wyoming to Njebraska 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- 

 dumentiwhiclvis short and scabrous; on the leaves, Iqngerand hispidulous on 

 the stem and, branches: cauline leaves oblon^-Janceolate, sessile by a broad, 

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

 riiosely disposed at the ends of tjie branches; involucres hemispherical; the 

 -bracts with long lanceolate spreading herbaceous tips, these glandular- 

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

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

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

 orado. . 



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



