gis CLCHORIACE NE Vou. UL. 
Leaves glabrous. , id ; 
Leaves entire to pinnatifid, not sagitate at base, 6. 1. canadensis, 
Leaves entire or denticulate, sagittate at base. a. L. sugtitifolia, 
LB, Achenes truncate, or narrowed into stout beaks; rays blue to white. 
Perennial; achenes thittencd. 8. L. pulehella, 
Annuals or biennials; achenes swollen, 
sili bright white. 
Achenes beakless ; leaves dentate, acuminate, 9g. Li willosa, 
Achenes beaked : leaves pinnatifid. 10, L. floridana, 
Pappus brown; achenes short-beaked. ii. Ly spicata, 
1. Lactuca virdsa L. Prickly or Wild 
Lettuce. Pig. 4ook. 
Lactuca viresa L. Sp. Pl 705.) 1753. 
MEM 
ies Si 
w 
AW 
Lactuea Serriola L, Cont. Pla: ag. 1756. 
Lactuea Scariola L. Sp. Pl Ed. a, rirg. 1763. 
Biennial, green and glaucous; stem stiff, leafy, 
usually paniculately branched, glhibrous through- 
out, or bristly-hirsute at the base, 2°=7° high. 
Leaves oblong or oblong-linecolate, spinulose- 
margined, denticulate or pinnatifid, sessile or 
auriculate-clasping, the lowest sometimes to’ 
long and 3’ wide, the upper much smaller; 
midrib spinulose or hispid; heads 2”~4" broad, 
6-12-flowered; very numerous in an open pan- 
icle; involucre cylindric, 1-14” thick, its outer 
bracts about one-third the length of the inner; 
rays yellow; achencs obovate-oblong, about as 
long as the filiform beak; pappus white. 
In fields and waste places, Vermont to Georgia, 
west to the Pacific Coast. A troublesome weed, 
Naturalized from Europe. Consists of several 
races, differing in the form, lobing and position of the leaves, Aug.—Sept. Milk- or horse-thistle. 
2. Lactuca saligna |.. Willow Let- 
tuce. lig, 4009. 
Lactuca saligna L. Sp. Pl. 796. 1753. 
Biennial, light green; stem slender, smooth 
or nearly so, 2° high or more, the very 
slender branches erect-ascending. Leaves 
glabrous, linear to oblong, 6’ long or less, 
runcinate-pinnatifid with pointed divergent 
lobes, or entire, sagittate at the hase, the 
midvein sometimes spinulose; panicles nar- 
row; heads about 3” broad, few-flowered ; 
involucre subcylindric; outer bracts much 
shorter than the inner; achenes oblong, 
about one-half as long as the filiform beak ; 
pappus white. 
Waste and cultivated grounds, Ohio. Nat- 
uralized from Europe. July~Aug. 
