304 coMfcosiMJ. (COMPOSITE FAMILY.) 



pus, its bristles falling separately. Leafy-stemmed herbs, with panicled heads ; 

 flowers of variable color, produced in summer and autumn. (The ancient 

 name of the Lettuce, L. sativa ; from lac, milk, in allusion to the milky juice.) 



1. SCARlOLA. Achenes very flat, orbicular to oblong, l-nerved on each face, 

 with a filiform beak ; biennial or annual ; cauline leaves sagittate-clasping. 



L. SCAR^OLA, L. (PRICKLY LETTUCE.) Stem below sparsely prickly- 

 bristly, as also the midrib on the lower face of the oblong or lanceolate spinu- 

 lose-denticulate vertical leaves; panicle narrow; heads small, 6- 12-flowered; 

 achenes striate. Waste grounds and roadsides, Atlantic States to Mo. and 

 Minn. (Adv. from Eu.) 



1. L. Canadtosis, L. (WILD LETTUCE.) Mostly tall (4-9 high), 

 very leafy, smooth or nearly so, glaucous; leaves 6-12' long, pale beneath, 

 mostly sinuate-pinnatifid, the upper lanceolate and entire (rarely all but the 

 lower narrow and entire) ; heads about 20-flowered, 3 - 6" long, numerous, in 

 long and narrow or diffuse panicles ; flowers pale yellow ; achene oval, rather 

 longer than the beak. Rich damp soil, borders of fields or thickets ; common. 



2. L. integrifolia, Bigel. Less leafy, 3-4 high, loosely branched 

 above or heads loosely panicled ; leaves undivided, oblong-lanceolate, pointed, 

 denticulate or entire ; flowers yellow or purplish. (L. Canadensis, var. integ- 

 rifolia, Torr. $ Gray.) N. Eng. to 111., and southward. 



3. L. hirsiita, Muhl. Rather few-leaved, 2-3 high, commonly hirsute 

 at base ; leaves hirsute both sides or only on the midrib, mostly runcinate-pin- 

 natifid ; heads in a loose open panicle ; achenes oblong-oval, about as long as 

 the beak; flowers yellow-purple, rarely whitish. (L. Canadensis, var. san- 

 guinea, Torr. $ Gray.) E. Mass, to Minn., and southward. 



4. L. Ludoviciana, DC. Glabrous, leafy, 2-5 high ; leaves oblong, 

 sinuate-pinnatifid and spinulosely dentate, ciliate ; heads in an open panicle ; 

 involucre more imbricate ; flowers yellow. Minn., Iowa, and southwest ward, 



2. LACTUCASTRUM. Achenes flat, lanceolate-oblong, tapering to a short 

 slender beak ; perennial ; flowers blue. 



5. L. pulch611a, DC. Pale or glaucous; stem simple, 1-2 high; 

 leaves sessile, oblong- or linear-lanceolate, entire, or the lower runcinate-pin 

 natifid ; heads few and large, racemose, erect on scaly-bracted peduncles ; in- 

 volucral scales imbricated in 3 or 4 ranks. (Mulgedium, Nutt.) Upper Mich, 

 to Minn. ; common on the plains westward. 



3. MULGiSDIUM. Achenes thickish, oblong, contracted into a short thick 

 beak or neck ; annual or biennial ; flowers chiefly blue. 



6. L. acuminata, Gray. Tall biennial (3-7 high), with many small 

 heads in a loose panicle, on diverging peduncles ; leaves ovate to oblong-lan- 

 ceolate, pointed, sharply and sometimes doubly serrate, sometimes hairy on 

 the midrib beneath, contracted into a winged petiole, the lowest occasionally 

 sinuate or cleft at base, and the cauline sagittate or hastate ; achenes beak- 

 less; pappus white. (Mulgedium, DC.) Borders of woods, N. Y. to 111. 

 and Fla. 



7. L. Floridana, Gaertn. Leaves all lyrate or runcinate, the upper 

 often with a heart-shaped clasping base; panicle larger; achenes distinctly 

 beaked ; otherwise as n. 6. Rich soil, Penn. to 111., and southward. 



