802 COMPOSITAE (COMPOSITE FAMILY) 



Rays 6 mm. or less long ; leaves slightly serrate . . 41. A. Trndeacanti. 

 Kays longer ; leaves entire . . (42) A. panieulatua, v. bettidiflorua. 

 Branches divaricate ; small heads in 1-sided racemes . 39. A. vimineuK. 

 Branches ascending, terminated by solitary heads (89) A. vimineua, v. saxatilis. 

 Rays violet or rose-pink (exceptionally white). 

 Leaves at most 4.5 cm. long, becoming revolute . . 55. A. nemoralia. 



Leaves longer, plane 44. A. junceus. 



V. Involucre more than 5 mm. high Y. 



Y. Bracts with definite firm subulate tips 82. A. polyphyllus. 



Y. Bracts without firm subulate tips Z. 

 Z. Leaves at most 4.5 cm. long. 



Stems many, rigid, from a woody caudex ; bracts firm, the 



inner blunt ; rays blue-violet 52. A. linariifolius. 



Stem single, from a slender rootstock ; bracts thin, linear- 

 attenuate ; rays rose-pink 65. A. nemoralia. 



Z. Leaves longer a. 

 a. Annuals, with inconspicuous rays. 



Bracts definitely imbricated, linear or linear-subulate . 57. A. aubulatua. 

 Bracts subequal, the outer foliaceous. 



Leaves linear-attenuate ; rays shorter than the style . 58. A. anguatua. 

 Leaves linear-oblanceolate to spatulate ; rays longer than 



the style 59. A.frondosua. 



a. Perennials, with mostly conspicuous rays ft. 

 b. Bracts firm, lanceolate. 



Bracts unequal, regularly imbricated, not foliaceous . 56. A. tenwifoliua. 

 Bracts subequal or imbricated, with spreading foliaceous 



tips ....!. A. paludosus. 



b. Bracts thin, linear or linear-lanceolate. 



Bracts with conspicuous elliptic or subrhombic green tips. 

 Heads terminating minutely foliose-bracteolate branch- 

 lets 88. A. dumoaus. 



Heads paniculate, or if few on leafy (not minutely 



foliose-bracteolate) branclles 43. A. aaUdfoliua. 



Bracts without conspicuous colored tips. 



Kays white ; bracts very narrowly linear-attenuate, 



regularly imbricated, 4-6 mm. long (42) A. panieulatua, v. bellidiflorua. 

 Rays violet or rose-pink ; bracts linear-lanceolate, less 



definitely imbricated, mostly longer . . .44. A.junceue. 

 U. Stem conspicuously pubesc"emt. 



Involucral bracts (or at least the outer ones) bristly-ciliate. 

 Leaves crowded, rigid ; rays white (rarely purple-tinged). 



Heads 5-6 mm. high 86. A. muttiflorua. 



Heads 7-9 mm. high 87. A. commutatua. 



Leaves not rigid ; rays blue 85. A. amethyatinua. 



Involucral bracts not bristly-ciliate. 

 Bracts with firm subulate tips ; short rays usually white. 



Involucre hemispherical or campanulas, as broad as high (33) A. ericoides, v. vittosiu. 

 Involucre turbinate, narrower than high . . (34) A. depauperatua, v. partiiceps. 

 Bracts thin, linear-attenuate, without firm subulate tips ; stem 



puberulent ; long rays violet or rose-pink . . . . 55. A. nemoralia. 

 T. Stem-leaves lanceolate or broader c. 

 o. Heads in flat-topped corymbs ; rays white or whitish (not blue or violet). 



Leaves rigid, linear-lanceolate ; pappus simple 58. A. ptarmicoidta. 



Leaves not rigid, broader ; pappus double. 



Involucre 8-4.5 mm. high ; leaves lanceolate to ovate . . .50. A. umbellatua. 

 Involucre 5-7 mm. high ; leaves obovate to oblong . . .51. A. infirmua. 

 C. Heads paniculate or racemose d. 

 d. Stems glabrous or essentially so . 

 6. Involucre 5 mm. or less high. 



Bracts with definite firm subulate tips 88. A. ericoidta. 



Bracts without firm subulate tips. 

 Heads in more or less 1-sided racemes. 

 Leaves narrowly lanceolate, scarcely serrate ; bracts linear- 

 attenuate 39. A. vimineua. 



Leaves broader, serrate ; bracts with the midrib dilated 



upward and rather conspicuous 40. A. lateriflorua. 



Heads on ascending-paniculate branches. 

 Bracts linear-attenuate. 

 Heads (including rays) 1-1.5 cm. broad ; bracts very 



slender and green 41. A. Tradeacanti. 



Heads larger ; bracts green chiefly at tip . . . . 42. A. paniculatus. 

 Bracts broad-linear or linear-oblong, with conspicuous 



elliptic or subrhombic green tips 48. A. aalicifoliua. 



6. Involucre more than 5 mm. high f. 



f. Bracts with definite firm subulate tips 82. A. polyphyllua. 



f. Bracts without firm subulate tips g. 

 g. Leaves on branchlets reduced to rigid subulate bracts. 



Perennial ; involucre 9 mm. or more high, of firm closely 



imbricated bluntish bracts 18. A. turbinelius. 



