COMPOSITE FAMILY. 197 



Obs. The flowers of this species are quite fragrant, and the heads 

 somewhat showy or conspicuous, being larger than those of any other 

 native thistle. It does not disseminate rapidly, and is therefore easily 

 kept in subjection by proper attention. 



4. C. horrid 'ulum, MX. Leaves semi-amplexicaul, pinnatifid, lanugi- 

 nous beneath the short segments toothed or incised, strongly spinose ; 

 involucre ovoid, large, with a verticil of pectinately spinose bracts at 

 base ; scales loosely imbricated, linear-lanceolate, tapering to a subulate 

 point, but scarcely spinose. 



SOMEWHAT RUGGED CIKSIUM. Yellow Thistle. 



Hoot biennial ? (perennial, DC.). Stem 18 inches to 2-3 feet high, rather stout, simple 

 or sparingly branched, arachnoid-lanuginous when young, finally smoothish. Leaves 

 4-12 inches long, hairy on the upper surface, lanuginous beneath, the segments pointed 

 with short rigid spines. Heads terminal, few, (often but one), nearly as large as in the 

 preceding species, surrounded at base by a whorl of numerous (10 -20 or 30) linear- 

 lanceolate bracts, about as long as the involucre, the bracts subpinnatifid or sinuate- 

 dentate, pectinately spinose, with the spines somewhat in pairs, or fascicled. Florets an 

 inch to an inch and a half long, pale yellow (sometimes purple ? or becoming purple in 

 drying?). 



Pastures and waste places : sea coast, from Massachusetts to Louisiana : introduced. 

 Fl. July. Fr. August. 



Obs. A rugged and repulsive plant, which is very common on the sea- 

 shore, and which it is very desirable should remain a stranger to our 

 farms. 



* * * Scales of the appressed involucre barely prickly pointed ; filaments 

 nearly smooth ; heads imperfectly dioecious. 



5. C. arven'se, Scop. Rhizoma creeping ; stem rather slender, striate- 

 angled, paniculately branched at summit ; leaves sessile, lance-oblong, 

 sinuate-pinnatifid and dentate, undulate, ciliate-spinose ; heads numerous, 

 small ; involucre oblong-ovoid ; scales appressed, lance-ovate, mucro- 

 nate, a few of the outer ones cuspidate-spinose. 



FIELD CIRSIUM. Canada Thistle. Cursed Thistle. 

 Fr. Chardon aux Anes. Germ. Die Acker Kratzdistel. 



Rhizoma perennial, creeping horizontally 6-8 inches below the surface of the ground, 

 and giving off numerous erect biennial branches. Stem 18 inches to 3 feet high, slender 

 and smoothish, the branches slender and lanuginous. Leaves 4-8 or 10 inches long, 

 sessile and slightly decurrent, smoothish on the upper surface, sometimes arachnoid- 

 lanuginous beneath, the radical ones curled or wavy. Heads half an inch to two-thirds 

 of an inch in diameter, terminal, sub-pedunculate ; scales smoothish, minutely ciliate. 

 Florets palish lilac-purple, with whitish anthers, perfect or the heads dioecious by abor- 

 tion. Akenes linear-oblong, slightly 4-cornered ; pappus finally longer than the florets. 



Fields and way-sides : Northern and Middle States : introduced. Native of Europe. 

 Fl. July. Fr. August. 



Obs. This is, perhaps, the most execrable weed that has yet invaded 

 the farms of our country. The rhizoma or subterranean stem (which is 

 perennial and very tenacious of life), lies rather below the usual depth of 

 furrows and hence the plant is not destroyed by common ploughing. 

 This rhizoma ramifies and extends itself horizontally in all directions, 

 sending up branches to the surface, where radical leaves are developed 



