CARDUACEAE. 357 



Stem-leaves lanceolate or oblong, usually distinctly triple-veined. 



Leaves thin, coarsely but not saliently toothed ; bracts over i mm. wide. 



^. M. Bigelovii. 

 Leaves thick with salient teeth ; plant very glandular ; bracts less than 

 I mm. wide. 

 Achenes glabrous or minutely pubescent ; stem glabrous below. 



3. M. varians. 

 Achenes strigose ; stem glandular hispid throughout. 



4. M. aspera. 

 Stem-leaves linear or oblanceolate, 1 -veined. 



Plant 2-5 dm. high ; heads numerous or several in a panicle or raceme. 

 Basal leaves spatulate, coarsely but not saliently toothed or entire ; 



inflorescence divaricate. 5. M. viscosa. 



Basal leaves narrowly oblanceolate, saliently toothed ; inflorescence 

 narrow ; plant about 2 dm. high. 6. M. viscosnla. 



Plant 1-2 (seldom 3) dm. high ; heads solitary or few ; basal leaves 

 broadly spatulate, toothed. 7. M. Pattersonii. 



Stem strigose-puberulent ; involucre slightly if at all viscid. 



8. M, rubricaulis. 

 Bracts linear with lanceolate or rhombic green tips, which are usually much 

 shorter than the straw-colored lower portion. 

 Leaves cinereous. 



Bracts canescent, scarcely at all viscid or glandular, g. M. canescens. 

 Bracts densely viscid or glandular, especially the tips. 



10. M. pulverulenta. 

 Leaves glabrous, or glandular-hispid or scabrous, not cinereous. 



Stem puberulent or glabrate, glandular only on the inflorescence. 

 Bracts slightly if at all squarrose. 



Stem slender with strongly ascending branches ; leaves subentire. 



11. M, glabrella. 

 Stem divaricately branched ; lower leaves sharply toothed. 



12. M.- ramosa. 

 Bracts strongly reflexed-squarrose. 



Leaves all, except those of the smaller branches, toothed. 



13. M. Selbyi. 

 Leaves all entire. 14. M. spectabilis. 



Stem densely glandular-hispid. 



Bracts more or less glandular-pubescent and with squarrose tips. 



15. M. cichoriacea. 

 Bracts grayish puberulent; tips not squarrose. 16. M. Fremontii. 



1. Machaeranthera tanacetifolia (H. B. K.) Nees. (Aster tanacetifolius 

 H. B. K.) In moist sandy soil from S. D. and Mont, to Tex. and Ariz. — 

 Denver; Wyoming line; foothills, west of Ft. Collins; New Windsor; Pueblo; 

 Rocky Ford; Spring Canon. 



■z. Machaeranthera Bigelovii (A. Gray) Greene. (Aster Bigelovii A. Gray) 

 On plains and foot-hills of Cblo. and N. Mex. — Alt. 5000-6000 ft. — Boulder. 



3. Machaeranthera varians Greene. On plains and mountains of Colo, and 

 N. M. — Alt. 6000-8000 ft. — Hinsdale Co. ; Colorado Springs ; near Pagosa 

 Peak; Bottomless Pit, Pike's Peak. 



4. Machaeranthera aspera Greene. On the mountains of Colo. — Alt. 8000- 

 10,000 ft. — Manitou; Ute Pass; Hinsdale Co.; Colorado Springs; Pike's Peak; 

 Engelmann Canon ; Como ; Georgetown ; mountains between Sunshine and 

 Ward. 



5. Machaeranthera viscosa (Nutt.) Greene. (Aster canescens viscosus A. 

 Gray) On dry hills and plains from Wyo. to Colo, and Calif. (?) — Alt. 

 6000-10,000 ft. — Colorado Springs ; Sangre de Cristo Creek ; Rogers ; Grecian 

 Bend, Pike's Peak; Trail Glen; Twin Lakes; Mt. Harvard; Table Rock. 



