COMPOSITAE (COMPOSITE FAMILY) 585 



and green: leaves lanceolate, pinnatifid and toothed, furnished with abundant 

 weak prickles: heads loosely cymose, 2-3 cm. high, dioecious; in staminate 

 plants ovate-globular, with the flowers well exserted; the pistillate oblong- 

 campanulate, the flowers less exserted; bracts of the involucre appressed, 

 short, with very small, weak, prickly points. A troublesome weed introduced 

 from Europe; becoming too common in Canada and our range. 



2. Carduus Parryi (Gray) Greene, Proc. Am. Acad. Sci. Phila. 362. 1892. 

 Green, lightly arachnoid and villous when young, 3-7 dm. high: leaves lanceo- 

 late, sinuate-dentate, not decurrent, moderately prickly: heads several and 

 spicately glomerate or more racemosely paniculate, more or less bractose- 

 leafy at base; accessory and outer proper bracts or some of them pectinately 

 fimbriate-ciliate down the sides; the innermost with more or less dilated or 

 margined, mostly lacerate-fimbriate tips: corollas pale yellow, the lobes longer 

 than the throat: pappus of fine, soft bristles, none of them obviously clavellate. 

 Cnicus Parryi. (C. viridiflorus Greene, in herb.) Colorado and Utah to New 

 Mexico and Arizona. 



3. Carduus americanus (Gray) Greene, 1. c. Stems rather slender, 3-8 dm. 

 high, branching above, the branches bearing solitary or scattered naked 

 heads: leaves white-tomentose beneath, lanceolate or broader, sinuately pin- 

 natifid or some merely dentate, others pinnately parted, weakly prickly: heads 

 erect, about 25 mm. high; principal bracts of the involucre naked-edged or 

 merely fimbriate-ciliate below, and the dilated scarious apex as broad as long, 

 fimbriate-lacerate, tipped with barely exserted cusp or mucro; innermost 

 with lanceolate, nearly entire, scarious tips: flowers ochroleucous: stronger 

 pappus-bristles dilated-clavcllate at tip. (C. Centaureae Rydb. Bull. Torr. 

 Bot. Club 28: 507. 1901; C. erosus Rydb. 1. c.; C. griseus Rydb. 1. c.) 

 Mountains of our range and northwestward. 



3a. Carduus americanus perplexans (Rydb.) A. Nels. Leaves oblanceolate 

 to lanceolate, merely toothed, and with weak, yellowish prickles: flowers 

 sometimes pink or purplish; the bracts slightly glandular on the back. C. 

 perplexans Rydb. 1. c. 32: 132. 1905.) Wyoming and Colorado. 



4. Carduus Hookerianus (Nutt.) Heller, Cat. N. A. Plants 7. 1898. 

 Arachnoid white-woolly to glabrate, stout: leaves pinnatifid; the short lobes 

 rather distant, sparsely prickly base little or not at all decurrent: heads few 

 and sessile in a terminal cluster or scattered, 3-4 cm. high, somewhat bracteose- 

 leafy at base; proper bracts tapering from a broadish base into a rather rigid, 

 subulate, prickly point, also somewhat viscidly long-woolly: corollas white or 

 whitish: pappus-bristles not clavellate-tipped. (C. Osterhoutii Rydb. 1. c. 32: 

 131. 1905; C. Kelseiji Rydb. Mem. N. Y. Bot. Gard. 1: 449. 1900.) Moun- 

 tains of our range and farther northward. 



4a. Carduus Hookerianus eriocephalus (Gray) A. Nels. More arachnoid- 

 pubescent on the involucre and the leaves usually greener and more glabrate. 

 (Cnicus eriocephalus Gray; Carduus scopulorum Greene, 1. c.; C. Tweedyi Rydb. 

 1. c.; C. araneosus Osterh. Bull. Torr. Bot. Club 32: 612. 1905; C. Eatonii 

 Gray, a form usually more glabrate on the involucre though often arachnoid- 

 woolly on the herbage; C. canovirens Rydb. 1. c. (?) ; C. pulcherrimus Rydb. Bull. 

 Torr. Bot. Club 28: 510. 1901.) Same range as the species. 



46. Carduus Hookerianus hesperius (Eastw.) A. Nels. The anthers 

 pubescent, not essentially different otherwise. (Cnicus hesperius Eastw. Proc. 

 Cal. Acad. Sci. III. 1: 122. 1898.) On Mt. Hesperus, Colorado. 



5. Carduus foliosus Hook. Fl. Bor. Am. 1: 303. 1833. Stems erect, strict, 

 striate, 3-5 dm. high, somewhat woolly, leafy to the cluster of few sessile 

 heads: leaves commonly elongated, linear-lanceolate, laciniately dentate, 

 with rather rigid prickles, arachnoid-tomentose beneath: heads broad, 4-5 

 cm. high, leaf y-bracteose ; involucral bracts thin-coriaceous, some of the inner 

 with more conspicuous, erose, scarious tips: corollas pale or white, with lobes 

 equaling or longer than the throat. [C. scariosus (Nutt.) Heller, is merely the 

 more tomentose form; C. coloradensis Rydb. 1. c. 132.] Colorado to Montana 

 and Oregon. 



6. Carduus Drummondii (T. & G.) Coville, Contr. U. S. Nat. Herb. 4: 142. 



