THISTLE FAMILY 977 



Plant 1-2 dm. (rarely 3 dm.) high; leaves thick, subentire, or with a few teeth: bracts 

 linear-lanceolate. 5. A. pumila. 



III. GRANULIFERAE. 

 One species. 6. A. granulifera. 



IV. GRACILES. 

 Upper leaves not linear. 



Bracts linear-lanceolate; leaves thin, usually more or less dentate. 7. A. gracilis. 

 Bracts oblanceolate ; leaves thick, usually entire. 8. A. puberula. 



Upper stem-leaves linear, much reduced. 9. A. arnoglossa. 



V. LATIFOLIAE. 



Leaves decidedly hairy, especially above. 10. A. Jonesii. 



Leaves nearly glabrous. 



Achenes slightly glandular-granuliferous, and with a few scattered hairs above. 

 Leaves not saliently toothed, merely denticulate. 11. A. ventorum. 



Leaves saliently and coarsely toothed. 12. A. Menziesii. 



Achenes glabrous; leaves more or less toothed. 13. A. latifolia. 



VI. DlVERSIFOLIAE. 



Leaves thin, nearly glabrous. 14. A. silvatica. 



Leaves thick, densely glandular-puberulent, at least above. 15. A. diversifolia. 



VII. LONGIFOLIAE. 



Involucre merely puberulent or glandular-granuliferous; leaves not caudate-attenuate; 



stem usually over 3 dm. high. 16. A. longifolia. 



Involucre copiously hirsute, as well as puberulent; leaves caudate-acuminate. 



17. A. caudata. 



VIII. MOLLES. 



Involucre villous, not at all glandular or viscid. 18. A. macilenta. 



Involucre more or less glandular or viscid. 



Involucre densely glandular-granuliferous, only with a few white hairs. 



19. A. arcana. 

 Involucre decidedly villous or hirsute, as well as glandular. 



Middle stem-leaves broadly ovate, less than 5 cm. long; stem 2-3 dm. high. 



Involucre less than 1 cm. high, villous at the base, only slightly glandular; 

 bracts broadly lanceolate. 20. A. coloradensis. 



Involucre 12-15 mm. high, densely glandular-hirsute; bracts narrowly ob- 

 lanceolate. 21. A. ovata. 

 Middle stem-leaves lanceolate, oblanceolate, or linear-lanceolate. 



Bracts oblanceolate, abruptly acuminate. 22. A. mollis. 



Bracts linear or lanceolate. 



Stem-leaves more or less sharply dentate, except at the base. 

 Leaves nearly glabrous,- except the margins. 



Stem-leaves ovate-lanceolate, broad at the base. 



23. A. amplexifolia. 

 Stem-leaves oblanceolate or narrowly lanceolate, narrowed at the 



base. 24. A. Macounii. 



Leaves decidedly pubescent, both villous and glandular-granuliferous. 



25. A. rivularis. 

 Stem-leaves entire, sparingly denticulate, densely glandular-puberulent. 



26. A. subplumosa. 



IX. FOLIOSAE. 



Pubescence of the leaves long and soft, villous. 



Bracts obovate-oblanceolate, mostly obtuse. 27. A. tomentulosa. 



Bracts oblong-lanceolate, acute. 



Plant sparingly pubescent, with long flat hairs; leaves long-acute. 



28. A. Chamissonis. 

 Plant densely pubescent with fine hairs; leaves acute or obtuse. 



Leaves broadly oblanceolate or lanceolate. 29. A. rhizomata. 



Leaves linear or lance-linear. 30. A. foliosa. 



Pubescence of the leaves very short and fine. 



Stem-leaves linear-lanceolate, usually entire or callous-denticulate; involucre rarely 



more than 1 cm. high. 



Pubescence of the involucre and peduncle very short and fine. 31. A. ocreata. 

 Pubescence of the involucre and peduncle longer and coarser. 32. A. celsar 

 Stem-leaves broadly lanceolate, more or less dentate; involucre usually more than 1 

 cm. high. 33. A. rubricaulis. 



X. ALPINAE. 



Stem-leaves ovate. 20. A. coloradensis. 



Stem-leaves linear to lanceolate. 



Leaves glabrate in age, at least above. 



Involucre and peduncle more or less glandular-puberulent; achenes hispidulous. 



9. A. arnoglossa. 

 Involucre more or less villous, at least at the base; achenes canescent. 



Leaves and lower part of the stem glabrous or nearly so; leaves mostly acute; 



bracts green. 



Leaves strongly 3-ribbed. 34. A. Rydbergii. 



Leaves faintly 3-ribbed. 35. A tennis. 



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