2*36 COMPOSITE, (composite family.) 



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

 siuia, Ton-. ^ Gray.) — Sandy ?hores of Lakes Michigan, Huron, and Superior. 

 3 C. undulatUS, Gray. White-woolli/ throughout, low and stout, leafy; 

 leaves lanceulate-ol>li)iig, partly clasping, undivided, undalate-pinnutifid , or rarely 

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

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

 \ ary much in size. 



4. C. altissimus, Willd Stem downy, branching (3-10° high), /eq/}/ 

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

 neath, oblong-ovate to narrou-lij lanceolate, undivided, sinuate-toothed, undulate- 

 pinnatijid, or twice pinna ti_/id, the lobes or teeth weakly prickly ; heads H-2' 

 high; flowers chiefly purple. (Cirsium, »S/>reH^.) — Fields and copses, Mass- 

 to Minn., and southward, 



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

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

 N. Eng. to 111., and soutliward. 



5. C, Virginianus, Tursh. 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 stnuate-lobed, sometimes the lower deeply sinuate-pinnatifid ; 

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

 — Woods and plains, ^"a., Ohio, and southward. 



-1-4- Leaves green both sides, or onlij 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 ivith 

 loose ivebby hairs beneath when young, deeply pinnatijid,the divisions lanceolate, 

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

 giabrate) 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 {\ -2° 

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

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

 hairy, pinnatijid, ivith short and cut very prickly-margined lobes ; outer scales 

 prick-ly-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. AKVENSis, Hoffm. (Canada Thistle.) Perennial, slender, 1 - 2° high, 



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

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

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

 troublesome weed, extremely difficult to eradicate. (Nat. from EuJ 



80. CARDUUS, Tourn. Pldmeless Thistle. 



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

 Otherwise as in Cnicus. (The ^ncient Latin name.) 



