GENUS 97.] 



THISTLE FAMILY 



1. Carduus lanceolatus L. Common 

 Bur or Spear Thistle. (Fig. 4058.) 



Carduus lanceolatus L. Sp. PI. S21. 1753. 



Cirsium lanceolatu> Scop. Fl. Cam. Ed. 2, 2: 130. 1772. 



Cnicus lanceolatus Willd. Prodr. Fl. Berol. 259. 1787. 



Biennial; stem stout, branched, more or less 

 tomentose, 3-5 high, leafy to the heads. Leaves 

 dark green, lanceolate, acuminate, deeply pinnatifid, 

 3 / -6 / long, or the lowest larger, decurrent on the 

 stem and branches, the lobes triangular-lanceolate, 

 tipped with stout prickles, the margins and decur- 

 rent bases bristly, the upper surface strigose-pubes- 

 Qent or hispid, the lower brown-tomentose and mid- 

 nerve pilose especially when young; heads mostly 

 solitary at the ends of the branches, i^ / -2 / broad, 

 T i^/_2 / high; bracts of the involucre cottony, nar- 

 rowly lanceolate, acuminate, all tipped with slen- 

 der erect or ascending prickles; flowers dark purple. 



In fields and waste places, Newfoundland to Georgia, 

 west to Minnesota, Nebraska and Missouri. Natural- 

 ized from Europe. Native also of Asia. Other names 

 are Plume, Bank, or Horse Thistle, Bell, Bird, Blue, Button, Bull or Roadside Thistle 



Carduus altissimus Lr. Tall or Roadside Thistle 



July-Nov. 



(Fig. 4059. ) 



Carduus altissimus L- Sp. PI. 824. 1753. 

 Cnicus altissimus Willd. Sp. PI. 3: 1671. 1804. 

 Cirsium altissimum Spreng, Syst. 3: 373. 1826. 



Biennial or perennial; roots often thickened; 

 stem pubescent, or tomentose, stout, branched, 

 leafy to the heads, 3-io high. Leaves ovate- 

 oblong or oblong-lanceolate, sessile, or slightly 

 clasping.sparingly pubescent above.densely white- 

 tomentose beneath, scarcely or not at all decurrent, 

 acute, spinulose-margined, entire, dentate with 

 bristle-pointed teeth or lobed, sometimes pinnati- 

 fid into oblong or triangular-lanceolate segments, 

 the lowest sometimes S / long, narrowed into mar- 

 gined petioles, the uppermost linear or lanceolate, 

 much smaller; heads about 2 / broad, \%'-2' high, 

 mostly solitary at the ends of the branches; outer 

 bracts of the involucre ovate or ovate-lanceolate, 

 firm, with a dark, slightly glandular spot at the 

 apex, tipped with short prickles, the inner linear- 

 lanceolate, acuminate, unarmed; flowers light 

 purple. 



In fields and thickets, Massachusetts to Minnesota, 

 Florida, Nebraska and Texas. Aug.-Sept. 



3. Carduus discolor (Muhl.) Nutt. 

 Field Thistle. (Fig. 4060.) 



Cnicus discolor Muhl.; Willd. Sp. PI. 3-" 1670. 1S04. 

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

 Cirsium discolor Spreng. .Syst. 3: 373. 1S26. 

 Cnicus altissimus var. discolor A. Gray, Proc. Am. 



Acad. 19: 57. 1883. 



Similar to the preceding species, but lower and 

 more leafy, seldom over 7 high. Leaves deeply 

 pinnatifid into linear, linear-lanceolate, or falcate, 

 prickly toothed segments. white tomentose beneath, 

 sessile, the basal ones sometimes I2 / long; heads 

 iy 2 , -2 / broad, about \Y 2 ' high, usually involucrate 

 by the upper leaves, mostly solitary at the ends of 

 the branches; outer bracts of the involucre coria- 

 ceous, ovate, slightly woolly, tipped with slender 

 bristles, which are longer than those of the preced- 

 ing species; inner bracts lanceolate, acuminate, un- 

 armed; flowers light purple or pink, rarely white. 



In fields and along roadsides, Quebec and Ontario to 

 Georgia, Minnesota, Nebraska and Missouri. July-Nov. 



