460 COMPOSITE. CiRsiuM. 



white {Mr. Oakes). — Muhlenberg's name is the most appropriate, and should 

 have been preserved. — Pasture Thistle. 



* * * Scales of the involucre ratlier loosely imbricated in feto series, tapering to a 

 subulate point : heads coTispicuously involucrate with a whorl of very spirwse bracts ! 



13. C. Iwrridulum (Michx.) : arachnoid-woolly when young, at length 

 somewhat glabrous; stem simple or sparingly branched; leaves partly 

 clasping, lanceolate, pinnatifid, the short lobes toothed or incised, strongly 

 spinose ; heads (large) surrounded by a whorl or dense cluster of pectinate- 

 spinose bracts about the length of the involucre, the prickles often fascicled ; 

 scales of the subglobose involucre linear-lanceolate minutely scabrous and 

 ciliate, tapering to a very sharp point, unarmed ; flowers pale yellow. — 

 Michx.! fl. 2. p. 90 ; DC. ! prodr. 6. p. 651. C. megacanthum, Nutt.Hn 

 trans. Amer.phil. soc. I. c. Carduus horridulus, Pers. syn. 2. p. 390. C. 

 spinosissimus, Walt. Cnicus horridulus, Pursh, fl. 2. p. 507 ,- Bigel. ! fl. 

 Bost. ed. 2. p. 291 ; Hook. ! compan. to hot. mag. 1. j). 48. C. spinosissir 

 mus, Darlingt. I fl. Cest. p. 438. — Varies, with the anthers and styles red- 

 dish or purple {Bigel. I. c. Oakes, 7iiss.), or with the corolla sometimes 

 changing to purple in drying {Barratt, mss.), or 



/3. Elliottii : flowers purple. — Cnicus horridulus, Ell. sk. 2. p. 272. 



Hills and poor soils, from the coast of Massachusetts! and Connecticut I to 

 Florida ! and Louisiana ! t^. Southern States, Elliott. Florida, Dr. Chap- 

 man I (Corolla in dried specimen light purple, the anthers yellowish.) 

 Lincoln County, N. Carolina, Mr. Curtis! Dr. Hunter! (Corolla, anthers, 

 and style deeply purple.) June-Aug. in the Northern, March-May in the 

 Southern States. — U or(|)? Plant 1-3 feet high; the large heads sub- 

 tended by 12-30 very spinose bracts; the exterior often pinnatifid. — A some- 

 what variable, but well-marked species, with the corolla and pappus much 

 larger than in C. spinosissimum, the heads not clustered, and the lobes of 

 the leaves rather distant. From the characters given, we suspect it is equally 

 distinct from C. glabrum, DC, of which we possess no specimen. — Yellow 

 Thistle. 



• ♦ * * Scales of the involucre loosely ivibricated in few series, somewhat unequal in 

 len<^th; the exterior with subiolate-spinescent tips : heads not involucr ate with bracts. 



14. C. remotifolium (DC. 1. c.) : stem tall, erect, striate, branching and 

 nearly naked above, somewhat arachnoid and hairy ; leaves remote, lan- 

 ceolate, sparsely hairy above, arachnoid-tomentose beneath, partly clasping 

 by an auriculate very spinose base, pinnately parted ; the segments deeply 

 2-3-cleft ; the lobes lanceolate, tipped with a spine, the margins somewhat 

 spinulose ; heads large, paniculate; the panicle nearly leafless ; scales of the 

 involucre somewhat arachnoid, nearly equal, straight, lanceolate-subulate, 

 loose, cuspidate ; the innermost membranaceous, much acuminated, unarm- 

 ed ; "flowers purplish." — Carduus remotifolius, Hook. fl. Bor.-Am. \. p. 

 302. Cirsium stenolepidum, Nutt. ! in trans. Amer. phil. soc. I. c. p. 419. 



Plains of Oregon, Douglas, Nultall ! — Stem purple above, 3-5 feet high. 

 Leaves somewhat resembling those of C. discolor. Heads as large as in C. 

 lanceolatum. 



§ 3. Heads by abortion dioecious: exterior scales of the involucre appressed, 

 unarmed, or the outermost tipped with a short prickle or bristle ; the innermost 

 with scarious tips : filaments nearly glabrous: roots creeping. (Cephano- 

 plos, DC.) 

 15. C. arvense (Scop.) : rhizoma creeping ; stem striale-angled, panicu- 



