320 



CICHORIACEAE. 



VOL. III. 



6. Lactuca canadensis L. Wild or Tall Lettuce. 



Wild Opium. Fig. 4073. 



Lactuca canadensis L. Sp. PI. 796. 1753. 

 Lactuca elongata Muhl. ; Willd. Sp. PI. 1525. 1804. 

 Lactuca canadensis niontana Britton, in Britton and 

 Brown, 111. Fl. 3: 274. 1898. 



Biennial or annual, glabrous throughout, some- 

 what glaucous ; stem leafy up to the inflorescence, 

 3-io high, branching above into a narrow pan- 

 icle. Leaves mostly sinuate-pinnatifid, those of 

 the stem sessile or auriculate-clasping, 2'-8' long, 

 the uppermost smaller, often lanceolate, acumi- 

 nate and entire, sometimes all lanceolate and en- 

 tire, the basal often 12' long, narrowed into peti- 

 oles ; heads numerous, 2"-3" broad ; involucre 

 cylindric, 4"-6" high, its outer bracts shorter than 

 the inner; rays yellow; achenes oval, flat, about 

 as long as the filiform beak; pappus white. 



In moist, open places, Nova Scotia to British Co- 

 lumbia, Georgia, Alabama, Louisiana, Arkansas and 

 Colorado. Santo Domingo. Trumpetweed, trumpet- 

 milkweed, trumpets, and fire-weed. Butter- or horse- 

 weed. Devil's-weed. Devil's-iron-weed. June-Nov. 



Lactuca Morssii Robinson, with blue rays, and 

 achenes 3 or 4 times longer than their filiform beaks, 

 may be a hybrid with L. spicata. 



7. Lactuca sagittifolia Ell. Arrow-leaved 

 Lettuce. Fig. 4074. 



L. sagittifolia Ell. Bot. S. C. & Ga. 2 : 253. 1821-24. 

 Lactuca integrifolia Bigel. Fl. Bost. Ed. 2, 287. 1824. 



Not Nutt. 1818. 

 L. elongata var. integ. T. & G. Fl. N. A. 2 : 496. 1843. 



Biennial ; stem glabrous throughout, or hirsute 

 below, leafy nearly up to the usually paniculate 

 inflorescence, 2-6 high. Leaves oblong, oblong- 

 lanceolate or lanceolate, acuminate or acute, en- 

 tire or denticulate, the lower rarely pinnatifid, 

 sometimes spinulose on the margins, those of the 

 stem sessile or sagittate-clasping, 3'-6' long, \'-\\' 

 wide, the basal and lower ones petioled ; heads 

 commonly very numerous, 2" -4," broad ; involucre 

 cylindric, 5"-7 ' high, the outer bracts shorter than 

 the inner ; rays yellow or reddish ; achenes oval, 

 flat, rather longer than their filiform beaks; pap- 

 pus white. 



In dry, open soil, New Brunswick and Ontario to 

 Georgia, Idaho and Kansas. Called also devil's-iron- 

 weed. July-Sept. 



8. Lactuca pulchella (Pursh) DC. Large- 

 flowered Blue Lettuce. Fig. 4075. 



Sonchus pulchellus Pursh, Fl. Am. Sept. 502. 1814. 

 Lactuca integrifolia Nutt. Gen. 2: 124. 1818. 

 Lactuca pulchella DC. Prodr. 7: 134. 1838. 



Perennial, glabrous throughout, somewhat glau- 

 cous; stem rather slender, leafy up to the corym- 

 bose-paniculate inflorescence, i-3 high. Leaves 

 linear-lanceolate, lanceolate or oblong, acute, en- 

 tire, dentate, lobed or pinnatifid, those of the stem 

 sessile or partly clasping, 2'-8' long ; 2"-i8" wide, 

 the lowest and basal ones sometimes petioled ; 

 heads mostly numerous, 6"-io" broad ; branches 

 and peduncles scaly; involucre well imbricated, 

 8"-io" high, its outer bracts successively shorter, 

 ovate-lanceolate; rays bright blue or violet; 

 achenes oblong-lanceolate, flat, twice as long as 

 their tapering beaks ; pappus white. 



In moist soil, western Ontario to British Columbia, 

 Michigan, Iowa, Kansas, New Mexico and California. 

 June-Sept. 



Lactuca campestris Greene, of the prairie region, 

 is described as differing from this by yellow rays. 



