270 CARDUACEAE 



Leaves more or less dentate or denticulate; stem 3-10 dm. high. 



105. S. exallatns. 

 Basal leaves entire; stem 2-3 dm. high. 106. S. FUntii. 



Basal leaf-blades spatulate to linear-oblanceolote or rarely lanceolate, gradually 

 tapering into the petioles. 

 Bracts about half as long as the fully developed disk. 



Plant 6-8 dm. high; inflorescence open, broad, about 2 dm. wide. 



107. S. latus. 



Plant 3-6 dm. high, slender; inflorescence 6-8 cm. broad, with a few heads. 



33. S. lupens. 

 Bracts more than half as long as the disk; inflorescence usually congested. 

 Leaves crisp, as well as the stem, conspicuously arachnoid-hairy, especially 

 when young; inflorescence dense; heads less than 1 cm. high. 



108. S. condensatus. 

 Leaves not crisp, only slightly villous when young; inflorescence more open; 



heads usually over 1 cm. high. 

 Leaves more or less dentate; inflorescence even in age a flat-topped 



corymb. 109. S. columbianus. 



Leaves merely callous-denticulate; inflorescence with a short-peduncled 

 terminal head and the lateral ones usually very long-peduncled. 



110. S. perplezus. 

 Heads solitary. 111. S. solitarius. 



XIX. Megacephali. 

 One species. 112. S. megacephalus 



XX. Vtjlgarbs. 

 One species. 113. .S. vulgaris. 



XXI. Palustbes. 

 One species. . 114. S. palustris. 



130. TETRADYMIA DC. 



Heads 4-flowered; bracts 4, lance-oblong; branches with scurvy-tomentose lines. 



Primary leaves linear to oblanceolate, permanently tomentose, more or less spreading. 

 Primary leaves oblanceolate. 1. T. inermis. 



Primary leaves linear. -■ 



Primary leaves 2-3 cm. long, straight. 2. T. canescens. 



Primary leaves 1-1.5 cm. long, arcuately reciu-ved, pimgent-pointed ; secondary 

 leaves fa.scicled. 3. T. linearis. 



Primary leaves linear -subulate. 



Primary leaves erect, slender; secondary leaves linear, or spatulate-linear, glabrate 



in age. 4. T. glabrata. 



Primary leaves spreading, stiff, spine-like; secondary leaves oblanceolate. 



5. T. Nuitallii. 

 Heads 5-9-flowered; bracts 5-6, at least the inner broadly oval; branches white-tomentose 

 throughout: plant spiny. 

 Spines 5-12 mm. long, more or less curved. 6. T. spinosa. 



Spines 15-30 mm. long, straight. 7. T. longispina. 



131. ARCTIUM L. Burdock. 



Involucre less than 2 cm. broad; inner bracts not exceeding the flowers. 1. A. minus. 

 Involucre 2.5 cm. broad or more; inner bracts at least equalling the flowers. 2. A. Lappa. 



132. SAUSSUREA DC. 



Leaves broadly ovate or the lower cordate; plant tall, 4-10 dm. high. 1. ,S. americana. 

 Leaves lanceolate to linear. 



Leaves lanceolate; stem 1-2 dm. high; heads crowded. 2. S. densa. 



Leaves very narrowly linear-lanceolate; stem 3-4 dm. high; heads long-pedunlced. 



3. S. remotifiora. 



133. CIRSIUM (Tourn.) Hill. Thistle. 



Bracts of the involucre conspicuously arachnoid-pubescent. 



Bracts not reflexed, only the tips sometimes spreading; stem arachnoid. 



Inner bracts conspicuously dilated. I. Parryana. 



Inner bracts not dilated. 



Leaves not conspicuously decurrent. II. Eriocephala. 



Leaves conspicuously decurrent, forming wings on the stem. 



III. Lanceolata. 

 Bracts squarrose and the lower reflexed. IV. Neomexicana. 



Bracts of the involucre not arachnoid-pubescent, or only slightly so on the margins. 

 Bracts all, except the outermost, with dilated fimbriate tips. V. Carlinoidia. 



Bracts all, except sometimes the very innermost, without dilated fimbriate tips. 

 Bracts neither with a dorsal glutinous ridge, nor a dark spot. 



Bracts, at least some of them, spinulose-ciUate on the mar^ns, not very un- 

 equal in length. VI. Leiocephala. 

 Bracts not spinulose-ciUate, regularly imbricate, the irmer much longer. 



Innermost innocuous bracts not conspicuously elongate, tlieir tips more or 

 less spreading, usually crisp or twisted, sometimes erose. 



VII. FOLIOSA. 



Innermost innocuous bracts elongate and usually more or less reddish,- 

 straight, neither dilated, crisp or twisted. VIII. PnLCHELL.\. 



