596 COMPOSITAE (COMPOSITE FAMILY) 



6a. Hieracium Scouleri griseum (Rydb.) A. Nels. The long white hairs 

 largely absent from the involucre. (H. griseum Rydb. Mem. N. Y. Bot. Card. 

 1: 465. 1900.) Colorado to Montana and westward. 



7. Hieracium cynoglossoides Arvet-Touv. Spicil. Hier. 20. 1881. More 

 or less pubescent with somewhat hispid hairs, and the inflorescence glandular; 

 stems 3-6 dm. high, numerous from the crown of a perennial root, leafy: 

 leaves lanceolate, mostly acute, 5-15 cm. long; the upper sessile by a narrow 

 base; the lower narrowed to a winged petiole: heads few-several in an open 

 corymbose cyme; involucre 12-1 6 mm. high; the linear-acute bracts and short 

 peduncles rather densely hirsute with short black hairs as well as glandular: 

 achenes rather short. In open woods; British Columbia to California and the 

 Rocky Mountains. 



104. LACTUCA L. LETTUCE 



Mostly tall herbs, with milky juice, leafy stems, and paniculate heads of 

 yellow, blue, or whitish flowers. Involucre glabrous and smooth, cylindra- 

 ceous, or in fruit somewhat conoidal, several-many-flowered. Achenes obcom- 

 pressed, and with a beak or narrowed summit, which is more or less expanded 

 at apex into a pappiferous disk. Pappus of bright white or rarely sordid bris- 

 tles, falling separately. 



Pappus brown; achenes beakless . . 1. L. spicata. 



Pappus bright white; achenes with a slender beak. 



Leaves spiny-margined and often with spiny midrib and veins. 



Leaves oblong-lanceolate, sinuate-pinnatifid . . . . 2. L. Scariola. 



Leaves oblanceolate, merely irregularly denticulate . . . 3. L. integrata. 

 Leaves not spinose. 

 Flowers yellow. 



Involucre irregularly calyculate . . . . . . 4. L. canadensis. 



Involucre imbricated . . . . . . . . 5. L. ludoviciana. 



Flowers blue (in no. 7 often purplish). 



Achenes striate-nervose . . . . . . . . 6. L. pulchella. 



Achenes 1 -3-nerved, transversely rugose 7. L. graminifolia. 



1. 'Lactuca spicata (Lam.) Hitch. Trans. Acad. St. Louis 5: 506. 1891. 

 Stem 3-10 dm. high, stout, leafy up to the pyramidal rather crowded panicle: 

 leaves ample, sinuately or runcinately pinnatifid, coarsely and irregularly or 

 doubly dentate; the upper cauline sessile by a mostly narrowed but auriculate 

 or partly clasping base: involucre oblong, 10 mm. high: flowers bluish to yel- 

 lowish or whitish: pappus sordid or fuscous. L. leucophaea. Across the con- 

 tinent from Oregon to the 'mountains of Carolina and northward. 



2. Lactuca Scariola L. Sp. PI. Ed. 2. 1119. 1763. Biennial, glabrous 

 throughout or hirsute at the base, green and glaucous; stem stout, 6-15 dm. 

 high, leafy, usually paniculately branched: leaves lanceolate to oblong, sinuate- 

 toothed or pinnatifid, sessile or auriculate-clasping, midrib below beset with 

 weak prickles: heads small, 6-12-flowered, very numerous, in an open panicle: 

 corollas pale yellow: achenes pale, obovate-oblong, several-nerved, margined, 

 about as long as the filiform beak. Becoming common in fields and waste 

 places; adventive from Europe. 



3. Lactuca integrata (Gren. & Godr.) A. Nels. Similar to the preceding 

 and confused with it: leaves oblong to oblanceolate, finely irregularly den- 

 ticulate, rarely slightly sinuate: achenes dark-colored. (L. virosa of Am. au- 

 thors, not L. virosa L.) A weed in waste ground; from our range to the At- 

 lantic States. 



4. Lactuca canadensis L. Sp. PI. 796. 1753. Biennial or annual, glabrous 

 and glaucescent; stem strict, 1-2 m. high, very leafy up to the elongated 

 narrow panicle: leaves mostly sinuate-pinnatifid, 1-3 dm. long, with margins 

 entire or sparingly dentate, and midrib naked or rarely some sparse bristles, 

 most of the cauline partly clasping by a sagittate or auriculate base: involucre 

 10-12 mm. high, 12-20-flowered: flowers yellow: achenrs blackish, obscurely 

 scabrous-ruguloKo, lightly 1-nerved on the middle of each face, broadly oval, 

 with distinct thin margins, rather longer than the beak; pappus white. Across 

 the continent. 



