COMPOSITAB (composite FAMILY) 597 



5. Lactuca ludoviciana (Nutt.) DC. Pi;odr, 9: 141. 1838. Biennial, 

 glabrous throughout, leafy up to inflorescence, paniculately branched, 6-15 

 dm. high: leave's oblong to ovate-oblong, acute or acutish, S-'IO cm. long, 

 auriculate-clasping, spinulose-denticulate to pinnatifid' with dpinulose seg- 

 ments: heads 6-10 mm. broad, numerous in an open panicle; mvolucre cy- 

 lindric or ovoid-cylindric, glabrous, the bracts successively shorter and broader, 

 the lower ones ovate: rays yellow: achenes oval to obovate, flat. — From Mon- 

 tana and the Dakotas to Texas. ' ' 



6. Lactuca pulchella (Pursh) DC. 1. c. 131. Perennial, glabrous, more or 

 less glaucous; stems erect, 3-'7 dm. tall, corymbosely paniculate above: leaves 

 5-20 cm. long, numerous, linear to lamceolate^ entire, toothed; or pinnatifid, 

 acute or obtuse, those of basal and lower stem leaves sometimes with winged 

 petioles, those of upper stem leaves sessile and partly clasping: peduncles often 

 copiously scaly: involucres 16-20 mm. long; inner bracts linear-lanceolate, 

 acute or obtusish: ligulesblue or violet: achenes black, the body rather feUip- 

 tic, ribbed, 4 mm. long, beak shorter than the body. (L. sylvatipa A. Nels. 

 Bull. Torr. Bot. Club 26: 486. 1899.) — ^In our range, and northward lalmost 

 across the continent. , ( 



7. Lactuca graminifolia Michx. Fl. Bor. Am. 2: 85. 1803. Blpnpial or 

 perennial, glabrous or nearly so, glaucescent; stems erect, 6-15 dm. tall, 

 paniculately branched above: leaf -blades elongated-linear or narrowly Hne'ar- 

 lanceolate, 10-40 cm. long, entire or with a few spreading or d.eflexed ,lob,es; 

 both the entire and pinnatifid types often on the same plant: peduncles often 

 with minute scales: involucres 12-15 mm. high; bracts linear-lanceolate to 

 lanceolate^ the inner scanous-ma,rgined: ligules pUTple, blue, or rarely white 

 or yellowish: achenes elliptic or elliptic-oblong, 4-4.5 mm. long, the beak 

 much shorter than the body. — In the southeastern part of oiu; range to South 

 Carolina and Texas. „ 



105. SONCHUS L. Sow Thistle 



Leafy-stemmed, coarse, succulent herbs, chiefly smooth and glaucous. 

 Heads cymose or umbellate, swollen at base or jugHshapedl; Involucral'bracts 

 few, thin, with many shorter ones at base; these becoming callous- thickened. 

 Flowers yellow. Achenes obcompressed, ribbed, not beaked. Pappus co- 

 pious, of cottony-white exceedingly soft and fine hairs, mainly falling together. 



Heads large; inyoluore glandular-pubescent 1 . S. arvensis. 



Heads medium-sized; involucre glabrous. 



Leaves prickly toothed; auricles rounded . . . . . 2. S; asper. 



Leaves with soft teeth; auricles acute . . . , . . .3. S. oleraceus. 



1. Sonchus arvensis L. Sp. fL 793. 1753. Rootstocks creeping; stems 

 5-10 dm. high, naked at summit, bearing few or several arid corynlbosely 

 paniculate showy heads: leaves runcinate-pinnatifid or, some undivided, 

 denticulate-spinulose; the cauline partly claspihg at base: peduncles and invo- 

 lucre more or less glandular-bristly; head 20-25 nim. high: achenes oblong, 

 about 10-costate, rugulose on the ribs. — This weed, naturalized from Europe, 

 is spreading in our range. 



2. Sonchus asper ,(L.) Hill, Herb. Brit. 1: 47. 1769. Stem often stout, 

 3-15 dm. high, from aji annualroot: leaves undivided, lobed, or pinnatifid, 

 spinulose-dentate; the lower spatulate to lanceolate, more or less distinctly 

 petioled; the upper clasping by an auriculatie base,, the auricles rounded: in- 

 volucre glabrous, about 12 mm', high; achenes smooth, 3-nerved on each side. 

 —Common in fields and waste places; na,turalized frofli Europe. 



3. Sonchus oleraceus L. Sp. PI. 794. 1753. Fibrous-rooted annual; stem 

 nearly simple, 5-20 dm. high: lower leaves petioled, lyrate-pinnatifid, 1-2 dm. 

 long, the terminal segment commonly large ,g.nd triangular, the margins deh- 

 ticmate with mucronate or scaTcely spiny teeth; thp upper pinnatifid, clasp- 

 ing by an auriculate or sagittate base, the auricles acute: mvolucre 12-16 mni. 

 high: achenes flat, longitudinally ribbed arid transversely rugose. — Common 

 in fields and waste places; naturalized from Eutope. 



