COMPOSITiE. 201 



* 

 Waste places. Penn. iVittAZ. July, Aug. '24-. — Jfea<fe with numerous purple 

 flowers. Involucre pale-brown, shining. Introduced from Europe. 



Brown Knap-weed. 



2. C. nigra Linn. : stem erect, branched ; leaves scabrous ; lower an- 

 gular-lyrate, petioled ; upper lanceolate ; scales of the involucre ovate, 

 fringed with capillary teeth ; rays none ; pappus very short, tufted. 



Fields. Mass. and Penn. July, Aug. %.. — Stem 2 — 3 feet high. Heads 

 terminal, solitary. Flowers purple. Scales of the involucre almost black, the 

 teeth brown, hitroduced from Europe and becoming in some places a trouble- 

 some weed. Black Knap-weed. 



3. C. Cijanus Linn. : cottony-tomentose ; stem erect, branched ; upper 

 leaves Unear, entire ; lowermost toothed or pinnatifid at base ; scales of the 

 involucre serrate ; pappus short. 



Cultivated grounds. N. S. July, Aug. (^.—Stem 2 — 3 feet high. Heads 

 m terminal peduncles ; rays few, spreading, bright blue ; dL^k flowers smaller, 

 purple. Introduced from Europe and naturalized in a few places. 



Com Blue-bottle. 



54. CNICUS. FaiK.— Blessed Thistle. 

 (From the Greek kvi^oj, to prick or wound.) 



Heads many-flowered ; the rays sterile, slender, nearly equal 

 to the disk. Involucre ovoid ; scales coriaceous, produced into 

 a long hard pinnated spinose appendage. Receptacle bristly. 

 Achenia smooth, striate. Pappus triple ; out«r series very short ; 

 intermediate of 10 long rigid bristles ; inner of 10 short bristles. 



C. benedidus Linn. D. C. Centaiirea benedicta. Limi. Ed. 2. 



Road sides ; rare. N. Y. June. Torr. 0. — Stem 1 — 2 feet high, branching. 

 Leaves clasping, somewhat decurrent and pinnatifid, the lobes spiny. Heads 

 large. Introduced. ComTnon Blessed Thistle. 



55. ONOPORDON. i^mw.— Cotton Thistle. 



(From two Greek words expressive of the efliect, ascribed by Pliny, to the ass 

 who eats the plant. Hook. Br. Fl.) 



Heads homogamous, many- and equal-flowered. Involucre 

 ovate-globose ; scales imbricate, coriaceous, terminating in a 

 lanceolate appendage bearing a spine at the summit. Recepta- 

 cle honey-combed. Achenia four-cornered, transversely ru- 

 gose. Pappus in several series, rough, deciduous. 



O. Acanthium Linn. : leaves ovate-oblong, sinuate and spinous, decur- 

 rent, woolly on both sides ; scales of the involucre linear-subulate, the 

 outer spreading and woolly at the base. 



Waste grounds. Mass. July. (^.—Stem 4 — 6 feet high, branched and 

 winged at the summit ; wings very spinous. Heads large, solitary. Flowers 

 purple. Introduced from Europe. Cultivated in Scotland as the Scotch Thistle. 

 Hook. Common Cotton Thistle. 



9* 



