948 



FLORA. 



* * Leaves, at least the lower, serrate. 



Stems usually pilose ; bracts very glandular. 31. A. major. 



Stems hispid-pubescent; bracts glabrous, or ciliate. 32. A. puniceus. 



2. Stem glabrous, or only sparingly pubescent above (yillous informs of A J o. 33). 



* Leaves sharply serrate. 

 Leaves tapering to the base. 



Outer bracts of the involucre foliaceous. 33. A. tardiflorus 



Bracts of the involucre narrow, not foliaceous. 



Leaves lanceolate to oblong-lanceolate, sessile. 32. A. puniceus. 



Leaves oval to ovate, the lower often petioled. 34. A. patitlus, 



Leaves abruptly contracted into margined petioles, often enlarged near the base, 



35- ^- pi'enanthoides. 

 Leaves strongly cordate-clasping; bracts green- tipped. 



. 36. A. laevis, 



* * Leaves entire, or very nearly so. 

 Involucre campanulate, its bracts appressed, green-tipped. 



f Bracts of the involucre with rhomboid green tips. 



Stem-leaves oblong, lanceolate or oval-lanceolate. 36. A. laevis. 



Stem-leaves elongated-lanceolate to linear. 37. A. concinnus. 



\ \ Bracts of the involucre linear, the tips narrower, lanceolate; stem-leaves linear ot 



narrowly lanceolate. 38. A, purpuratus. 



% Involucre hemispheric. 

 t Bracts of the involucre narrow, not foliaceous. 



(a) Bracts in several series, unequal. 



Bracts linear-subulate; leaves narrowly linear. 39. A. junceus. 



Bracts lanceolate, linear, or spatulate; leaves lanceolate to linear. 



Western dry-soil plant, 3-6 dm. tall; leaves 2. 5 7.5 cm long. 40. A. adscendens. 



Eastern swamp plant, 6-15 dm. tall ; leaves 5-15 cm. long. 41. A. Xovi-Belgii, 



(b) Bracts in only i or 2 series ; leaves linear to lanceolate. 



42. A. longifolius. 

 f f Bracts of the involucre green, foliaceous ; western. 



43. A.foliaceus. 

 C. Leaves sessile, or pstided, not at all clasping, or scarcely so. 



i. Leaves silKy, silvery or canescent ou botli sides, entire. 



Heads corymbose-paniculate ; bracts oblong ; achenes glabrous. 44. A. sericeus. 

 Heads in a narrow raceme; bracts linear; achenes silky. 45. A. coucolor. 



2. Leaves neither silky, silvery nor canescent, often toothed. 



* Rays normally purple, blue, pink, or violet: not white. 

 Leaves bristly ciliate, linear, rigid; western species. 46. A. Fendleri. 



Leaves not bristly ciliate. 



f Tips of the involucral bracts strongly squarrose. 

 Leaves linear to linear-oblong, rigid, obtuse, entire ; heads 2.5 cm. broad. 



47. A. grandiJJorus. 

 Leaves lanceolate to oblong, at least the lower dentate. 



Involucre hemispheric, or nearly so ; heads 2.5 cm. broad or more. 



Bracts of the involucre glandular. 48. A. spectabilis. 



Bracts of the involucre ciliate, or glabrous. 49. A. sitrcnlosns. 



Involucre turbinate; heads 12-18 mm. broad. 50. A. gracilis. 



f f Tips of the involucral bracts appressed, or erect (except in forms of No. 52), 

 (a) Bracts of the involucre coriaceous or herbaceous, oblong, linear, lanceolate, 01 



spatulate. 

 Bracts of the involucre coriaceous, obtuse. 



Involucre hemispheric; leaves oblong, sharply serrate ; stem smooth. 



51. A. Radula. 

 Involucre turbinate. 



Leaves ovate-oblong, the lower dentate; stern rough. 52. A. Herveyi. 

 Leaves linear-oblong, entire, ciliolate. 53. A. turbinellus. 



Bracts of the involucre herbaceous, acute. 



Involucral bracts foliaceous; leaves oblong, very rough. 54. A. Nebraskensis. 

 Involucral bracts not foliaceous; leaves linear or the lower spatulate, not rough. 

 Pubescent ; inner involucral bracts abruptly acuminate or obtusish. 



55. A. Pricea e. 

 Glabrous ; involucral bracts all narrowly linear, gradually acuminate. 



56. A. Kentuckiensis. 

 Bracts of the involucre rigid, lanceolate, large, acute; leaves linear. 



57. A. paludosus. 

 (b) Bracts of the involucre linear-subulate, membranous, acute. 



8. A, nemorafa, 



