296 COMPOSITE. (COMPOSITE FAMILY.) 



again pinnatifid divisions, with revolute margins; flowers cream-color. (Cir 

 sium, Torr. fy Gray.) Sandy shores of Lakes Michigan, Huron, and Superior. 



3. C. undul&tus, Gray. White-woolly throughout, low and stout, leafy ; 

 leaves lanceolate-oblong, partly clasping, undivided, undulate-pinnatifid, or rarely 

 pinnately parted, moderately prickly; flowers reddish-purple. (Cirsium, 

 Spreng.) Islands of L. Huron to Minn., Kan., and westward. The heads 

 vary much in size. 



4. C. altissimus, Willd. Stem downy, branching (3-10 high), leafy 

 quite to the heads ; leaves roughish-hairy above, whitened with close wool be- 

 neath, oblong-ovate to narrowly lanceolate, undivided, sinuate-toothed, undulate- 

 pinnatifid, or twice pinnatifid, the lobes or teeth weakly prickly; heads H-2' 

 high; flowers chiefly purple. (Cirsium, Spreng.) Fields and copses, Mass, 

 to Minn., and southward. 



Var. discolor, Gray. Stem 2-6 high ; leaves nearly all deeply pinnat- 

 ifid into lanceolate or linear lobes. (Cirsium discolor, Spreng.) Common; 

 N. Eng. to 111., and southward. 



5. C. Virgini&nus, Pursh. Stem woolly, slender, simple or sparingly 

 branched (1 -3 high), the branches or long peduncles naked ; leaves lanceolate, 

 green above, whitened with close wool beneath, ciliate with prickly bristles, 

 entire or sparingly sinuate-lobed, sometimes the lower deeply sinuate-pinnatifid ; 

 heads small ; outer scales scarcely prickly ; flowers purple. (Cirsium, Michx.) 

 Woods and plains, Va., Ohio, and southward. 



*-- Leaves green both sides , or only with loose cobwebby hairs underneath ; heads 

 large ; scales scarcely prickly-pointed. 



6. C. mtltiCUS, Pursh. (SWAMP THISTLE.) Stem tall (3-8 high), 

 angled, smoothish, panicled at the summit ; branches sparingly leafy, bearing 

 single or few rather large heads ; leaves somewhat hairy above, whitened with 

 loose webby hairs beneath when young, deeply pinnatifid, the divisions lanceolate, 

 acute, cut-lobed, prickly-pointed ; scales of the webby and glutinous (sometimes 

 glabrate) involucre closely appressed, pointless or barely mucronate; flowers 

 purple. (Cirsium, Michx.) Swamps and low woods ; common. 



7. C. pumilus, Torr. (PASTURE THISTLE.) Stem low and stout (1 -2 

 high), hairy, bearing 1-3 very large heads (If broad), which are often leafy- 

 bracted at the base ; leaves green, lanceolate-oblong, partly clasping, somewhat 

 hairy, pinnatifid, with short and cut very prickly-margined lobes ; outer scales 

 prickly -pointed, the inner very slender ; flowers purple or rarely white (fragrant- 

 2' long). (Cirsium, Spreng.) Dry fields, N. Eng., near the coast, to Penn. 



* * * * Outer scales of the appressed involucre barely prickly -pointed ; heads, 

 imperfectly dioecious, small and numerous. 



C. ARVENSIS, Hoffm. (CANADA THISTLE.) Perennial, slender, 1-2 high, 

 the roots extensively creeping ; leaves oblong or lanceolate, smooth, or slightly 

 woolly beneath, smuate-pinnatifid, prickly-margined; flowers rose-purple. 

 (Cirsium, Scop.) Cultivated fields, pastures, and roadsides, common ; a most 

 troublesome weed, extremely difficult to eradicate. (Nat. from Eu.) 



80. CARDUUS, Tourn. PLUMELESS THISTLE. 



Bristles of the pappus naked (not plumose), merely rough or denticulate. 

 Otherwise as in Cnicus. (The ancient Latin name.) 



