THISTLE FAMILY 269 



stem-leaves not with dilated-auricled bases 



Stem-leaves entire or nearly so, not auricled. 74. 5. Tracyi. 

 Stem-leaves more or less lyrate-pinnatifld. 



Basal leaf-blades suborbicular, sinuate. . 75. S. Pammelii. 



« Basal leaf-blades oval or ovate. 



Plant densely cespitose; bracts 5—6 mm. Ions;. 



76. S. aquariensis. 

 Plant not densely cespitose; bracts 7-8 mm. long. 



77. S. Farriae. 

 Heads discoid. 



First basal leaves reniform. 78. S. nephrophyllus. 



None of the leaves reniform. 



Plant stout; stem-leaves with broad laciniate segments. 79. S. idahoensis. 

 Plant slender; stem-leaves with narrow segments. 



Plant yellowish or light green; bracts not purple-tinged. 



68. S. flavulus. 

 Plant dark green. 



Basal leaves crenate; head 8-10 mm. high; bracts purple-tinged, linear. 



80. S. pauciflorus. 

 Basal leaves wavy; heads about 6 mm. high; bracts broadly lanceolate or 

 oblong, not purple-tinged. 81. S. fedifolius. 



XIII. SUBNUDI. 



One species. 82. S. subnudus. 



XIV. Andicolae. 



Blades of the basal leaves orbicular, rounded, subcordate, obovate or cuneate, toothed 

 at least at the apex, obtuse. 

 Heads 7-8 mm. liigh, several in a dense cluster. 83. S. Wardii. 



Heads 9-12 mm. liigh, solitary or a few in an open corymb. 



Rays golden yellow. 84. S. petrocallis. 



Rays paler yellow. 



Basal leaf-blades sub-reniform; plant .subacaulescent. 85. S. Porteri. 

 Basal leaf-blades oval or obovate; plant with a short stem. 

 Involucre hemispherical to campanulate. 



Flowering stems about 2 dm. liigh; heads 9-10 mm. high; basal leaves 



crenate-serrate, except at the very base ; achenes hispidulous on the 



angles. 86. S. cognatus. 



Flowering stems less than 1.5 dm. high; heads 10-12 mm. high; achenes 



glabrous. 



Stem-leaves linear or linear-oblanceolate, if toothed, only at the 



apex. 87. S. pentodontus. 



Stem-leaves lanceolate, the lower more or less pinnately lobed or 

 toothed. 88. S. ovinus. 



Involucre turbinate. 89. S. turbinatus. 



Blades of the basal leaves elliptical to Unear, entire or very rarely some of them 3-toothed 

 at the apex, acute. 

 Plant in age nearly glabrous, monocephalous, 5-6 cm. high. 90. S. alpicola. 

 Plant more or less permanently floccose, with usually several heads, over 1 dm. high. 



91. S. werneriaef alius. 



XV. Hydrophili. 



Leaves thick, entire cr rarely minutely denticulate; inflorescence dense. 



Heads discoid; stem -leaves more or less clasping. 92. S. pacificus. 



Heads radiate; stem- leaves narrowed at the base. 93. S. hydrophilus. 



Leaves dentate; inflorescence open. 94. S. hydrophiloides. 



XVI. Cr.\ssuli. 

 Stem-leaves linear or linear-lanceolate. 



Stem naked above; disks S-10 mm. broad. 95. S. pereziifolius. 



Stem leafy; disks 12-15 mm. broad. 96. S. lapalhif alius. 

 Stem-leaves ovate or ovate-lanceolate. 



Leaves firm; bracts very tliick and fleshy. 97. S. crassitlus. 



Leaves thin; bracts not very thick. 98. S. semiamplexicaulis. 



XVII. Rapifolii. 

 One species. 99. S. rapifolius. 



XVIII. INTEGERRIMI. 



Heads several. 



Bracts of the involucres narrowly linear-lanceolate, long-attenuate. 

 Bracts without black tips; leaves entire-margined. 



Plant low, 1-3 dm. high, simple, more or less villous. 



100. S. Scribneri. 

 Plant tall, 4-10 dm. high, branched, glabrous. 101. S. integerrimus. 



Bracts usually black-tipped; leaves more or less dentate or denticulate. 

 Leaves thick, the basal ones obovate, dentate. 102. S. Hookeri. 



Leaves thin, the basal ones oblanceolate or spatulate, merely denticulate. 



103. S. dispar. 

 Bracts of the involucres linear or oblong, rather abruptly acute, with a lanceolate or 

 triangular black tip. 

 Basal leaf-blades cordate to broadly oval, rather abruptly contracted into the 

 petioles. 

 Rays ochroleucous or white. 104. S. Leiberr/ii. 



Rays deep yellow. 



