384 COMPOSITAE cARDuus 



coriaceous or chartaceous, mostly acuminate weak-prickly, pointed or 

 innocuous with more scarious and sometimes, obviously dilated and erose- 

 fimbriate tips : corollas white to rose-purple, with lobes usually shorter 

 than the throat. From the Arctic sea-shore to California and the Rocky 

 Mountains. 



C. foliosus Hook. Fl. i, 303. Stems erect, robust, striate, somewhat 

 woolly, leafy to the cluster of a few sessile heads, 12-18 inches high : 

 leaves commonly elongated, linear-lanceolate, laciniately dentate, with 

 rather rigid prickles, arachnoid-tomentose beneath : heads broad, inch and 

 a half high leafy-bracteose : involucral bracts thin-coriaceous : corollas 

 pale or white, with lobes equalling or longer than the throat. Idaho to 

 the Rocky Mountains. 



4_ H_ ^_ jjggjg large or comparatively small : involucral bracts 



closely appressed. coriaceous or thickish, commonly with a glandular 



or viscid ridge, short line, or brpad spot on the back near the summit. 



C. undulatus Nutt. Gen. ii, 130. Persistently white-tomentose, 1-4 

 feet high : leaves lanceolate or oblong-lanceolate, sessile or decurrent, or 

 the lowest petioled, undulate, lobed or pinnatifid the lobes dentate, trian- 

 gular, often very prickly : heads about 3 inches broad, nearly as high, soli- 

 tary at the ends of the branches: principal bracts of the involucre mostly 

 thickened on the back by the broad glandular-viscid ridge, comparatively 

 narrow, tipped with short spreading prickles : corollas rose color or pale 

 purple to white, with lobes equalling or longer than their throats. Dry 

 prairies, Brit. Columbia to Oregon, New Mexico and Lake Huron. 



Var. megacephalus Greene 1. c. Stouter, usually broader-leaved; 

 with broad heads 2 inches or more high. Idaho to Minnesota and Texas. 



C. Breweri Greene 1. c. 363. Usually white-tomentose, 4-10 feet high: 

 leaves mostly elongated-lanceolate, conspicuously prickly: heads panicu- 

 late, sometimes very numerous, subsessile, an inch or more high: bracts 

 of the globular involucre much appressed, firm coriaceous, with an oblong 

 or oval greenish viscid-glandular spot near the tip ; outer ones ovate to 

 oblong, abruptly tipped with a rather slender spreading prickle : corollas 

 pale purple or whitish, the lobes shorter than the throat. Moist places, 

 southern and eastern Oregon to California and Nevada. 



90 SILYBUM Gaertn. Fr. ii, 308. (Milk Thistle.) 



Annual or biennial herbs with large alternate clasping sinuate- 

 lobecl or pinnatifid white-blotched leaves, and large discoid heads 

 of purple tubular flowers, solitary at the ends of the branches, 

 involucre broad, subglobose ; its bracts rigid, imbricated in many 

 series, the lower ones fimbriate-spinulose at the broad triangular 

 summit, the middle ones similar but armed with stout spreading 

 or recurved spines; the inner ones lanceolate. Receptacle flat, 

 densely bristly. Corollas with slender tube and deeply 5-cleft 

 limb. Filaments united 'below, glabrous. Anthers sagittate at 

 base. Style nearly entire. Achenes obovate-oblong, compressed, 

 glabrous, surmounted by a papillose ring. Pappus-bristles in 

 several series, flattish, barbellate or scabrous. 



S. Marianum Gaertn. 1. c. 378. Stout, 2-4 feet high, little branched, 

 plabrate or glabrous: leaves oblong-lanceolate, prickly, sinuate or pinna- 

 tifid, the lower often a foot long, green blotched with white along the 

 veins: heads about 2% inches broad: corollas rose-purple, deeply cleft: 

 pappus-bristles white, barbellate. Waste places and road-sides, Brit. CO" 

 luhjbia to California. Naturalized from Europe, 



