40S 



I ( iMI'i IS] I \l 



Vol. III. 



37. A. junceus. 



38. A. adscendens. 



39. A. novi-belgii. 



40. ^4. longifolius. 



41. /L foliaceus. 



42. /4. phyilodes. 



scriceus. 

 concoior. 



A. Fendleri. 



(a) Bracts in several series, unequal. 

 Bracts linear-subulate; leaves narrowly linear. 

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

 Western dry soil plant, 1 2 tall; leaves 1' 3' long. 

 Eastern swamp plant, 2-$ tall ; leaves 2'-6' long. 



(b) Bracts in only 1 or 2 series ; leaves linear to lanceolate, 

 it Bracts of the involucre green, foliaceous; western. 

 Leaves lanceolate, firm ; heads few. 

 Leaves oblong-lanceolate, thin ; heads many. 



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

 1. Leaves silky, silvery or canescent on both sides, entire, 

 II. .i.ls corymbose-paniculate; bracts oblong; achenes glabrous. 43. / 



Heads in a narrow raceme ; bracts linear ; achenes silky. 44. /. 



2. Leaves neither silvery, silky nor eanescent, entire or toothed. 

 * Bracts of the involucre with herbaceous tips. 

 t Bracts thin or coriaceous, relatively small. 

 t Leaves bristly-ciliate, linear, rigid ; western species. 45. 

 }$ Leaves not bristly-ciliate. 

 Tips of the involucral bracts spreading (little spreading in A. Radula, erect or spreading in 

 A. Herveyi) ; heads large and showy ; rays violet to purple. 

 Leaves linear to linear-oblong, rigid, obtuse, entire ; heads 2' broad. 46. A. grandiflorus. 



Leaves lanceolate to oblong, the lower sparingly dentate. 

 Basal leaves with margined petioles. 



Involucre hemispheric to campanulate; heads 1' or more. 



Bracts of the involucre glandular. 47. 



Bracts of the involucre ciliate, or glabrous. 

 Involucre turbinate ; heads 6"-g" broad. 49. 



Basal leaves with unmargined petioles. 

 Leaves oblong-lanceolate, sharply serrate, rugose, the basal usually wanting. 50. 

 00 Involucral bracts all appressed (except in A. multiftorus and A. comtnutatus, small-headed species). 

 A Involucre top-shaped ; rays violet. 52. A. turbinellus. 



AA Involucre hemispheric to campanulate ; rays mostly white, sometimes purple. 

 Heads unilaterally racemose. 



Stem leaves oval, oblong, or lanceolate, serrate, or chiefly so. 



Stem pubescent or glabrate. 53. 



Stem villous ; leaves narrowly lanceolate, thin. 54. 



Stem leaves linear-lanceolate to linear, nearly entire; stem glabrate. 55. 



Heads not unilaterally racemose, mostly paniculate. 



Involucral bracts spatulate, mostly ciliate, somewhat spreading, at least the outer obtuse ; 

 roughish-puberulent. 

 Heads 3" 4" broad, numerous; rays 10-20. 

 Heads 5" 8" broad, relatively few ; rays 20-30. 

 Involucral bracts appressed, acute. 



Heads solitary at the ends of very small-leaved branchlets. 

 Heads paniculate. 



Stem leaves lanceolate, serrate or entire. 

 Heads 8"-io" broad. 



Plants glabrous, or sparingly pubescent above. 



Leaves firm, roughish or rough ; rays often purplish ; involucral bracts acute. 



59. A. salicifohus. 

 Leaves thin, smoothish ; rays chiefly white ; involucral bracts acuminate. 



A. spec'abilis. 

 A. surculosus. 

 A. gracilis. 

 A. Herveyi. 

 A. Radula. 



A. lateriflorus. 

 A. hirsiiticaulis. 

 A. vimineus. 



56. 



57- 



plants 



multiftorus. 

 commutatus. 



58. A. dumosus. 



Plant puberulent all over. 

 Heads 6"-8" broad ; stem leaves narrowly lanceolate. 

 Stem leaves linear-lanceolate to subulate, mostly entire. 

 Heads scattered, 6"-9" broad ; upper leaves linear. 

 Heads numerous, 4" 7" broad ; upper leaves subulate. 

 Involucre subhemispheric, 2 J / 2 "-3" high. 

 Rays usually white; heads 4" 7" broad. 

 Paniculately branched, bushy. 

 Simple, or with slender ascending branches. 

 Rays purple; heads 8" 12" broad. 

 Involucre top-shoped, 2^" high or less. 

 Plant pilose-pubescent, i 1 / 2 ''-2 high. 

 Plant glabrous, very slender, 1 high or less, 

 tt Bracts stiff, relatively large; leaves narrow, rigid, entire. 



60. 

 61. 

 62. 



paniculatus. 



missouriensis. 



Tradescanti. 



63. A. Faxoni. 



64. 

 65. 

 66. 



67. 

 68, 



A. ericoides. 

 A. Pringlei. 

 A. Priceae. 



A. parviceps. 

 A. depauperatus. 



[Genus Heleastrum DC] 

 69. A. paludosus. 



** Bracts of the involucre without herbaceous tips. 



Bracts linear-subulate, acuminate. 



Leaves firm, 3' long or less, entire or sparingly serrate. 70. A. nemoralis. 



Leaves thin, 6' long or less, sharply serrate. 71. A. acuminatus. 



Bracts oblong or oblong-lanceolate, obtuse or acutish ; leaves narrow, entire. [Genus Unamia 



Greene.] 72. A. ptartnicoides. 



D. Leaves fleshy, narrow, entire; plants of salt marshes or saline soil (No. 74 sometimes in 



non-saline situations). 



Perennial ; heads 6"- 12" broad ; involucral bracts lanceolate, acuminate. 73. A. tenuifolius. 



Annuals; head 3"-$" broad; involucral bracts linear-subulate. [Genus Tripolium Nees.] 



Involucre campanulate ; disk-flowers more numerous than the rays ; rays about 2" long. 



74. A. exilis. 



Involucre cylindraceous ; disk-flowers fewer than the very short rays. 75. A. subulatus. 



