Genus 97. ] 



THISTLE FAMILY. 



489 



13. Carduus muticus (Michx.) Pers. Swamp Thistle. (Fig. 4070.) 



Cirsium muticum Michx. Fl. Bor. Am. 2: 89. 1803. 

 Carduus muticus Pers. Syn. 2: 386. 1807. 

 Cnicus muticus Pursh, Fl. Am. Sept. 506. 1814. 



Biennial; stem woolly or villous when 

 young, becoming glabrate, slender, striate, 

 leafy, paniculately branched above, 3-S high. 

 Leaves densely white-tomentose beneath when 

 young, sometimes becoming glabrous on both 

 sides, deeply pinnatifid into lanceolate or ob- 

 long, entire, lobed or dentate, spiny segments 

 usually tipped withslender prickles; basal leaves 

 petioled, 4 / -S / long, those of the stem sessile 

 and smaller; heads about i% f broad and high, 

 solitary, terminal, naked-peduncled, or with a 

 few small bract-like leaves near the base; outer 

 bracts viscid, appressed, more or less cottony, 

 ovate or ovate-lanceolate, the inner linear-lance- 

 olate, acute, all unarmed; flowers purple. 



In swamps and moist soil, Newfoundland to 

 Florida, Northwest Territory and Texas. July-Oct. 



Carduus muticus subpinnatifidus Britton. 

 Leaves lobed, not deeply pinnatifid, green, and nearly glabrous on both sides. New Jersey to 

 West Virginia. 



14. Carduus arvensis (L,.) Robs. Canada Thistle. Creeping Thistle. 



Serratula arvensis L- Sp. PI. 820. 1753- 

 Cirsium arvense Scop. Fl. Carn. Ed. 2, 2: 126. 1772. 

 Carduus arvensis Robs. Brit. Fl. 163- 1777. 

 Cnicus arvensis Hoffm. Deutsch. Fl. Ed. 2, 1: Part 2, 

 130. 1804. 



Perennial by horizontal rootstocks, forming 

 patches, nearly glabrous; stems striate, i-3 high, 

 branched above. Leaves sessile and slightly clasp- 

 ing, lanceolate or oblong-lanceolate, deeply pin- 

 natifid into very prickly, lobed or dentate segments; 

 basal leaves sometimes petioled, $ / -S / long; heads 

 numerous, corymbose, dioecious, i' broad or less, 

 nearly 1/ high, purple or white, staminate heads 

 globose, corollas projecting; pistillate heads ob- 

 long- campanulate, corollas shorter, the long pap- 

 pus conspicuous; outer bracts ovate or ovate-lan- 

 ceolate, appressed, tipped with short prickly 

 points, inner bracts of the pistillate heads linear, 

 elongated. 



In fields and waste places,Newfoundland to Virginia, 



Minnesota and Nebraska. In many places a pernicious 



Called also Way 



June-Sept. 



weed. Naturalized from Europe. 



or Cursed Thistle, Corn or Hard Thistle 



15. Carduus nutans L,. Musk Thistle. 



Plumeless Thistle. (Fig. 4072.) 

 Carduus nutans L. Sp. PI. 821. 1753- 



Biennial, branched, sparingly tomentose, 2-3 

 high. Leaves lanceolate in outline, deeply pinnat- 

 ifid, acuminate, 3 / -6 / long, the lobes triangular, 

 very prickly; heads long-peduncled, solitary at the 

 end of the stem or branches, i^ / -2 / ^ / broad, nod- 

 ding, purple, rarely white, fragrant; bracts of the 

 involucre in many series, lanceolate, long-acumi- 

 nate, the prominent mid-nerve prolonged into a 

 prickle, or the inner nerveless and awned; pappus- 

 bristles io // -i / long, white, very minutely barbed. 



In waste places, Pennsylvania and New Jersey to 

 New Brunswick, and in ballast about the sea ports. 

 Naturalized or adventive from Europe. Native also 

 of Asia' Bank or Buck Thistle, Queen Ann's Thistle. 

 July-Oct. 



