COMPOSITAE. 



VOL. III. 



4. Cirsium virginianum (L.) Michx. Vir- 

 ginia Thistle. Fig. 4639. 



Carduus virginianus L. Sp. PI. 824. 1753. 



Cirsium virginianum Michx. Fl. Bor. Am. 2 : 90. 1803. 



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



Biennial; stem slender, naked or scaly above, 

 pubescent or somewhat tomentose, simple or 

 branched, 2-3i high. Leaves oblong, oblong- 

 lanceolate, or the lowest slightly spatulate, ses- 

 sile, or somewhat clasping, not decurrent, acute 

 or acutish, spinulose-margined, entire, lobed or 

 pinnatifid into triangular-lanceolate lobes, the 

 lower sometimes 8' long and 2' wide, narrowed 

 into margined petioles, all pubescent or glabrate 

 above, and densely white-tomentose beneath ; 

 heads long-peduncled, i'-ii' broad, about i' high; 

 outer bracts of the involucre not coriaceous, lan- 

 ceolate or ovate-lanceolate, tipped with weak short 

 bristles, the inner ones very narrow and merely 

 acuminate; flowers purple. 



In dry woods and thickets, Virginia to Kentucky, 

 Ohio, Florida and Texas. April-Sept. 



5. Cirsium Pitcher! (Torr.) T. & G. Pitcher's Thistle. Fig. 4640 



Cnicus Pitcheri Torr.; Eaton, Man. Ed. 5, 180. 1829. 

 Cirsium Pitcheri T. & G. Fl. N. A. 2 : 456. 1843. 

 Carduus Pitcheri Porter, Mem. Torr. Club 5 : 345. 1894. 



Biennial, persistently white-tomentose throughout ; 

 stem stout, leafy up to the heads, usually branched, 

 i-2 high. Leaves sessile, partly clasping or slightly 

 decurrent, pinnately divided into narrowly linear, 

 entire lobed or pinnatifid, acute sparingly prickly seg- 

 ments, 2"-3" wide, with revolute margins ; basal 

 leaves often 12' long; heads solitary or several and 

 racemose-spicate at the ends of the branches, about 

 ij' broad; outer bracts of the involucre ovate-lan- 

 ceolate, sparingly pubescent and tomentose-ciliate, 

 glutinous on the back, tipped with short spreading 

 bristles, the inner narrowly lanceolate, acuminate or 

 sometimes tipped with weak prickles; flowers cream 

 color. 



Shores of Lakes Michigan, Huron and Superior. June- 

 Aug. 



6. Cirsium undulatum (Nutt.) Spreng. 

 Wavy-leaved Thistle. Fig. 4641. 



Carduus undulatus Nutt. Gen. 2: 130. 1818. 

 Cirsium undulatum Spreng. Syst. 3: 374. 1826. 

 Cnicus undulatus A. Gray, Proc. Am. Acad. 10 : 42. 1874. 

 Cnicus undulatus var. megacephalus A. Gray, Proc. Am. 



Acad. 10: 42. 1874. 

 Carduus undulatus megacephalus Porter, Mem. Torr. 



Club 5: 345. 1894. 



Biennial, persistently and densely white-tomentose 

 throughout, or the upper surfaces of the leaves at 

 length green and glabrous; stem stout, leafy, usually 

 branched, i-3 high. Leaves lanceolate or oblong- 

 lanceolate in outline, acute, sessile or decurrent, or 

 the lowest petioled, undulate, lobed or pinnatifid, the 

 lobes dentate, triangular, often very prickly; basal 

 leaves often 8' long; heads ii'-3' broad, and nearly 

 as high, solitary at the ends of the branches ; outer 

 bracts of the involucre ovate or ovate-lanceolate, 

 firm, glutinous on the back, tipped with short spread- 

 ing prickles, the inner ones lanceolate, acuminate ; 

 flowers purple or pink. 



On plains and prairies, Lake Huron to Assiniboia, Alberta, Kansas, New Mexico and Arizona. 

 June-Sept. 



