404 COMPOSITE lactuca 



EONCHUS 



L. scariola L. Sp. ed. 2 1119. Biennial : glabrous throughout or hir- 

 sute at the base ; green and glaucous : stem stout, 2-7 feet hieh, leafy, usu- 

 ally paniculately branched : leaves lanceolate to oblong, with spinulose- 

 denticulate margins, sometimes 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 obovate-oblong, several-nerved, margined, about as long as the 

 filiform beak. Becoming common in fields and waste places. Introduced 

 from Europe. 



L. sativa The common Lettuce is common along the Rail Road in the 

 southern part of Oregon but is hardly naturalized. 



L. Canadensis L. Sp. ii, 796. Biennial or annual: glabrous and 

 glaucescent : stem strict, 4-12 feet high, very leafy up to the elongated 

 narrow panicle: leaves mostly sinuate-pinnatifid, 6-12 inches 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 auricu- 

 late base : involucre half-inch or less high, 12-20-flowered : flowers yellow, 

 achenes blackish, obscurely scabrous-rugulose, lightly 1-nerved on the 

 middle of each face, broadly oval, with distinct thin margins, rather long- 

 er than the beak: pappus white. Moist woods, Oregon and Washington 

 to the Eastern States. 



L. sagittifolia Ell. Bot S. C. & Ga ii, 253. Glabrous; 3-6 feet high, 

 leafy nearly to the usually loosely paniculate inflorescence : leaves oblong 

 to lanceolate, 3-10 inches long, acute or acuminate, entire or denticulate, 

 the lower sometimes pinnatifid, whitish beneath, midrib naked : involucre 

 5-7 lines high : flowers pale yellow or purplish : achenes oval, thin-margined 

 longer than the beak. Open ground, Idaho to the Eastern States. 



§ 2 Lactucastrum Gray Syn. Fl. i, pt, 2, 443. Root perennial. 

 Involucre well imbricated. Achenes lanceolate-oblong, flat, not 

 margined, tapering into a beak not longer than the breadth of the 

 body. 



L. pnlchella DC. Prodr. vii, 134. Very glabrous: stems 1-5 feet high, 

 leafy up to the open corymbiform panicle : leaves from linear-lanceolate to 

 narrowly oblong, entire or runcinate-dentate, or some lower ones pinnati- 

 fid ; cauline sessile but not auriculate at base : branches of the loose panicle 

 scaly : involucre 8 lines high, 12-15-flowered, its outer bracts ovate-lanceo- 

 late : flowers bright blue or violet-purple : achenes barely 2 lines long, 

 striate-nerved, the tip of the short beak soft and usually whitish. Alluvial 

 ground, Oregon to Brit. Columbia, Hudson Bay and Michigan. 



§ 3 Mulgedium Gray 1. c. Biennial or perennial herbs with 

 usually bluish flowers, Achenes thickish, oblong, with some 

 strong ribs and nerves : contracted at summit into a short stout 

 beak, or into a mere neck under the dilated apex. 



L. spicata Hitchc. L. leucophxa Gray. Stem usually stout, 3-12 

 feet high, leafy up to the panicle : leaves 3-12 inches long by 2-6 broad, 

 sinuately or runcinately pinnatifid, coarsely and irregularly or doubly den- 

 tate ; upper cauline sessile by a mostly narrow but auriculate or partly 

 clasping base : heads in a pyramidal crowded panicle : involucre oblong, 5 

 lines high: flowers bluish: achenes narrowed at summit to a short but 

 manifest neck. Moist ground, Oregon to Brit. Columbia and the E. States. 



113 SONCHUS Tourn. L. Gen. n. 908. 

 Succulent herbs with leafy stems, alternate spinulosely or cili- 



