This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Biennial or annual, glabrous throughout, somewhat glaucous; stem leafy up to the inflorescence, 3°-100 high, branching above into a narrow panicle. Leaves mostly sinuate-pinnatifid, those of the stem sessile or auriculate-clasping, 2'-8' long, the uppermost smaller, often lanceolate, acuminate and entire, sometimes all lanceolate and entire, the basal often 12' long, narrowed into petioles; 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 Columbia, 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.
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, entire or denticulate, the lower rarely pinnatifid, sometimes spinulose on the margins, those of the stem sessile or sagittate-clasping, 3'-6' long, 1/2-1 1/2' 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; pappus white.
In dry, open soil, New Brunswick and Ontario to Georgia, Idaho and Kansas. Called also devil's-iron-weed. July-Sept.
Perennial, glabrous throughout, somewhat glaucous; stem rather slender, leafy up to the corymbose-paniculate inflorescence, 1°-3° high. Leaves linear-lanceolate, lanceolate or oblong, acute, entire, dentate, lobed or pinnatifid, those of the stem sessile or partly clasping, 2'-8' long; 2"-18" wide, the lowest and basal ones sometimes petioled; heads mostly numerous, 6"-10" broad; branches and peduncles scaly; involucre well imbricated, 8"-10" 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.