CiRsiuM. COMPOSITiE. 461 



late ; the branches somewhat woolly : leaves oblong or lanceolate, sessile, 

 glabrous, sometimes a little woolly beneath, sinuate-pinnatifid, undulate, 

 spinose; heads small and numerous; scales of the involucre ovate-lanceo- 

 late, mucronate, a few of the exterior cuspidate-spinose ; flowers pale purple, 

 or rarely whitish. — DC ! prodr. 6. p. 6i3. Serratula arvensis, Linn.; FL 

 Dan. t. 644. Carduus arvensis. Smith, Engl. hot. t. 975 ; Hooh. ! Ji. Bor.- 

 Am. I. p. 301 ; Darlingt. ! ji. Cest. p. 439. Cnicus arvensis, Pursh,Jl. 2. 

 p. 506 ; Bigel.Jl. Bost. ed. 2. p. 291. Breea arvensis, Less. syn. p. 9. 



Cultivated fields of the Northern and Middle States ! introduced with grain 

 from Europe, and in many places becoming an extremely troublesome weed. 

 Also Canada! to Saskatchawan and Newfoundland; probably indigenous. 

 July-Aug. — 2i Too well known to our farmers, under the name of Canada 

 Thistle, or Cursed Thistle. 



X Little-Tcnown species. 



16. C. foliosum {TiC. I.e.): stem erect (simple?), robust, striate, some- 

 what woolly; leaves erect, the upper very numerous and exceeding the 

 heads, flaccid, irregularly sinuate-toothed, unequally ciliate with rather rigid 

 spines, sparingly hairy above, pale and arachnoid-tomentose beneath ; heads 

 large, glomerate in the axils of the uppermost leaves ; scales of the involucre 

 linear, appressed ; pappus very Qopious. Hook. — Carduus foliosus, Hook.fl. 

 Bor.-A7n. 1. p>- 303. 



Prairies of the [Northern] Rocky Mountains, Drummond. — " The stems 

 are singularly erect and straight ; the leaves also erect, 6-8 inches long, the 

 uppermost very numerous, considerably exceeding and almost concealing the 

 flowers." Hook. 



17. C. edule (Nutt.) : annual or biennial, nearly smooth ; leaves lanceo- 

 late, clasping, moderately pinnatifid ; the segments obtuse, almost equally 2- 

 lobed, spinescent and spinulose-ciliate ; heads terminal, glomerate, sessile, 

 3-5 together ; involucre subglobose, arachnoid-tomentose ; the scales linear- 

 lanceolate, tipped with short erect spines. Null, in trans. Amer. phil. soc. 

 \n. ser.) 7. p. 420. 



Common in the plains of the Oregon and the Blue Mountains, Nuttall. — A 

 robust plant 3-4 feet high, somewhat succulent, with purple flowers, nearly 

 as large as in C. lanceolatum. Filaments hairy. The young stems are 

 eaten raw by the aborigines. Nutt. — Probably the same as the C. fohosum. 

 Hook. An edible thistle is mentioned by Lewis and Clarke. 



18. C hrevifolium (Nutt.) : stem slender, nearly terete, and as well as the 

 lower surface of the leaves canescently tomentose, bearing 2-3 heads; leaves 

 oblong-lanceolate, clasping, green and nearly glabrous above, sinuaie-pin- 

 natifid, with shallow simple or 2-cleft lobes, tipped with spines, and with 

 spinose serratures ; involucre ovate, naked ; the scales lanceolate, glutinous, 

 smooth, terminating in small erect spines ; flowers ochroleucous. Nutt. in 

 trans. Amer. phil. soc. I. c. j). 421. 



Plains of the Rocky Mountains, Nuttall. — Leaves about half an inch wide, 

 2-3 inches long. Allied to C. Virginianum. Nutt. 



19. C. canescens (Nutt.) : perennial, dwarf, slender, canescently tomentose; 

 leaves lanceolate, decurrent, pinnatifid; the undulate segments oblong, 

 2-cleft, spinescent, and with spiny serratures; heads few (3-5), conglome- 

 rate, sessile; involucre slightly pubescent; the scales lanceolate, with rigid 

 erect spines. Nutt. in trans. Amer. phil. soc. I. c. p. 420. 



Arid deserts of the Platte, Nuttall. — Root creeping as in C. arvense. Stern 

 8-10 inches high. Leaves 3-4 inches long, about an inch wide, nearly 

 while on both sides, but most so beneath, decurrent with narrow spiny 



