486 



COMPOSITAE. 



[Vol. III. 



4. Carduus Virginianus L. Virginia 

 Thistle. (Fig. 4061.) 



Carduus Virgiuiauus'L. Sp. PI. 824. 1753. 

 Cirsium Virginianum Miclix. Fl. Bor. Am. 2: 90. 



1803. 

 Ciiicus yirgintaiius Vursh, Fl. Am. Sept. 506. 1814. 



Biennial; stem slender, naked or .scaly above, 

 pubescent or somewhat tomenlo.se, simple or 

 branched, 2°-t,}4° 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 S' long and 2' wide, narrowed 

 into margined petioles, all pubescent or glabrate 

 above, and densely wliite-tomentose beneath; 

 heads long.peduncled, I'-i'/i' broad, about i' 

 high ; outer bracts of the involucre not coriaceous, 

 lanceolate or ovate-lanceolate, tipped with weak 

 short bristles, the inner ones very narrow and 

 merely acuminate; flowers purple. 



In dry woods ,ind thickets, Virg;iiiia to Kentucky, 

 Ohio, Florida and Texas. April-Sept. 



(Fig. 4062.) 



5. Carduus Pitcheri (Torn ) Porter. Pitcher's Thistle 



CniC7is 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. 1S94. 



Biennial, persisteutly white-tomentose throughout; 

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

 l°-2° high. Leaves sessile, partly clasping, or 

 .slightly decurrent, pinnately divided into narrowly 

 linear, entire lobed or pinnatifid, acute sparingly 

 prickly segments 2"-3" wide, with revolute mar- 

 gins; basal leaves often 12' long; heads solitary or 

 several and racemose-spicate at the ends of the 

 branches, about 1%' broad; outer bracts of the in- 

 volucre ovate-lanceolate, 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. Carduus undulatus Nutt. Wavj'- 

 leaved Thistle. (Fig. 4063.) 



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



Cnicus undulalusX. Gray, Proc. Am. Acad. 10:42. 1874. 



Biennial, persistently and densely white-tomen- 

 tose throughout, or the upper surfaces of the leaves 

 at length green and glabrous; stem stout, leafy, usu- 

 ally branched, i°-3° high. Leaves lanceolate or 

 oblong-lanceolate in outline, acute, .sessile or decur- 

 rent, or the lowest petioled, imdulate, lobed or pin- 

 natifid, the lobes dentate, triangular, often very 

 prickly; basal leaves often S' long; heads about 2' 

 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 spreading prickles, the inner 

 ones lanceolate, acuminate; flowers purple or pink. 



On plains and prairies. Lake Huron to the Northwest 

 Territorj- and British Columbia, south to Kansas, New 

 Mexico and OrcKOU. June-Sept. 

 Carduus undulatus megacephalus (A. Gray) Porter, Mem. Torr. Club, 5: 345. 1894. 

 Cnicus vndnlalus var. »:eg;acephalus A. Gray, Proc. Am. .\cad. lo: 42. 1874. 

 Heads larger than in tiie type, 2'-3' broad. Minnesota to Idaho and Arizona. 



