1210 



CARDUACEAE 



Stem and branches with appressed pubescence : leaves 



nearly glabrous. 76. A. multiflorus. 



Stem and branches with spreading pubescence : leaves 



manifestly pubescent and ciliate. 77. A. exiguus. 



Bracts acute or merely obtusish. 

 Racemes or panicles secund. 



Cauline leaves linear to linear-lanceolate, minutely 



hack-toothed. 



Plants sparsely branched, and with few heads. 78. A. racemosm. 

 Plants profusely branched, heads very numerous. 79. A. vimineus. 

 Cauline leaves oblong or lanceolate, dentate or ser- 

 rulate. 

 Stem and branches sparingly pubescent or gla- 



brate. 80. A. lateriflorus. 



Stem and branches villous ; as also the midrib 



beneath. 81. A. hirsuticaulis. 



Racemes or panicles not definitely one-sided. 



Cauline leaves oval. 82. A. spatdliformia. 



Cauline leaves narrow. 



Cauline leaves entire, somewhat linear or linear- 

 lanceolate. 



Heads white (sometimes becoming purplish). 



Heads numerous, 8-14 mm. broad : leaves 



of the upper parts of the stem and 



branches subulate. 83. A. ericoides. 



Heads more scattered, 12-18 mm. broad : 



upper cauline leaves linear. 

 Branches divaricate, rigid, prolonged : 



rameals subulate. 84. A. juniperinus. 



Branches often upturned or subcorym- 



bose : many rameals flat, linear. 85. A. Faxoni. 



Heads chiefly colored. 



Rays crimson or pink. 86. A. Priceae. 



Rays violet. 



Leaves rough-pubescent all over, above. 87. A. Batdwinii. 

 Leaves smooth and glabrous, except the 



margins. 63. A. elodes. 



Cauline leaves serrate. Longifolial Asters, Nos. 



88-92. 

 Heads mostly less than 16 mm. broad. 



Heads abundant, closely panicled. 88. A. Ti-adescanti. 



Heads remotely panicled or sparse. 89. A. agrostifolius. 



Heads mostly over 16 mm. broad. 



Rays usually white : leaves scarcely firm. 



Leaves smoothish, elongated. 90. A. paniculatus. 



Leaves and stem minutely pubescent. 91. A. Missouriensin. 

 Rays usually bluish violet. 



Leaves firm, rough or roughish. chiefly 

 hack-serrate, the margins not 

 thickened. 92. A. salicifolius. 



Leaves with thickened and scabrous 

 margins, but smooth and glabrous 

 elsewhere. 62. A. Novi-Belgii. 



tf Heads numerous, in a terminal umbel-like corymb. Mis- 

 cellaneous Asters, Nos. 93-102, begin here. 

 Leaves typically linear, entire or nearly so : bracts linear- 

 oblong, obtuse. 93. A. ptarmicoides. 

 Leaves typically oblong-acuminate to elliptic, coarsely 



toothed : bracts linear-subulate. 94. A. acuminatus. 



Basal and lower cauline leaves grass-like. 



Leaf-blades entire. 95. A.paludosus. 



Leaf-blades with few or several spinuliform teeth. 



Heads sessile and subremote in the upper axils. 96. A. spinulosut. 



Heads terminal, solitary or clustered. 97. A. eryngiifolius. 



** Leaves fleshy or succulent : plants sometimes armed with spines. 

 Stem solitary, its base not woody : plant unarmed. 



Plants perennial from a caudex or rootstock : heads mostly over 12 



mm. wide. 



Leaves chiefly basal and linear, long-petioled. 98. A. CJiapmani. 



Leaves scattered, linear and sessile. 99. A. tenuifolius. 



Plants annual : heads mostly less than 10 mm. wide. 



Involucre campanulate : rays fewer than the disk-flowers. 100. A. exilis. 



Involucre cylindraceous : fays more numerous than the disk- 

 flowers. 101. A. subulatus. 

 Stems several from the woody persistent base : plant spine-armed. 102. A. spinositf. 



1. Aster divaric&tus L. Stems tufted, 4-6 dm. tall, assurgent, flexuous, brittle, 

 terete, glabrate at maturity : leaf -blades thin, smoothish, slender-petioled, ovate-lanceolate, 

 closely and saliently dentate with sharp teeth, incurved-acuminate, the basal sinus moder- 

 ately large, broad and deep : leaves of the inflorescence (bracteals} typically small, sessile, 

 short, ovate-acute to short-oval, nearly entire : corymb broad, flattish, repeatedly and 

 widely forked, the slender branches long, divergent : heads 18-25 mm. broad : ray-flowers 

 chiefly 6-9 ; ligules white, or rarely roseate or slightly crimson : young involucre short-cyl- 



