590 COMPOSITAE 
Perennial with deep vertical root and horizontal creeping root-branches; flowering-heads 4-5 oe broad. 
arvensis. 
Ber Ae or rage al; ee ng-heads less than 4-5 cm. broad. 
Au s of the leaves acute; achenes striate, agantagai! wrinkled. 
ome blades serra ead r with lobes 0.5—3 cm. wide; achenes about as broad as thick. 2. S. oler 
Leaf- yer s pinnately parted with narrow me mostly less than 0.5 cm. wide; achenes ya Bees. slightly = 
k 
ag of the — rounded; achenes usually conspicuously 3-nerved, smooth or ness A, pt ae 
4 Sper 
1. Sonchus arvénsis L. Perennial Sow-thistle. Fig. 6022. 
Sonchus arvensis L. Sp. Pl. 793. 1753. 
Perennial with c reeping rootstocks ; stems nth dm. high, glabrous below, Seal tre mabe 
bristly above, pi ae the pedun cles. Lea s 3-10 cm. lon ng, runcinate — ee d or sometim 
merely dentic ulate, the margins a, -denticuate, the lower narrowed t Sasa! petioles the 
upper sensiie, — ulate- aos at base and rounded; inflor ce seeiitelah es mbose or even 
subumbelliferous ; involucres 14-20 m me nine the chelated shins ate at apex, cinahieslae-liintly 
as are also the Stduiihens ligules scieht: orange- -yellow, the heads up to 3-5 cm. broad at ant si 
achenes cs 8-10 mn “ong ned, 2 2.5-3.5 mm. long, usually 5-ribbed on each face, yale tie rugose 
papp ng. 
ralized fro rope but not common in the Fecite ote Puget Sound ar d Whitman County, Wash- 
ing Mths Ppa Sing and west = the Cascade Mou n Willa eats Valles: occurring sporadically in Cali- 
forma whoa it has been collected at a few scattered pager throughout the state. April—July. 
us arvensis var. poms Guenth. Graeb. & Wim , Enum. Stirp. Phan. Siles. 127. 24. (Son 
chus A nm nosus Bieb. Taur. Cauc. 2: 238.. 1808.) Resemblin ng ome i arvensis var. arvensis in habit and variability 
of ave: “son lacking the ‘glandula ar bristles on involucre and peduncles of that taxon, tle a pbmrioe! are often m 
ale. uropean weed more common in north — = northeastern United States, and occ ng sporadi cally 
in the Pacific States as a weed but less common n S. arvensis var. pieeasis 
2. Sonchus oleraceus L. Common Sow-thistle. Fig. 6023. 
Sonchus oleraceus L. Sp. Pl. 794. 1753. 
Plants usually stoutish, 5-10 dm. high, sparingly leafy, glabrous or with a = glandular hairs 
on the peduncles and involuc cres, oiten glaucescent. Leaves variable in shape, ovoid or narrower, 
si rari or runc a -pinnatifid, toothed but not prickly-margined, amplexicaul, ine hacen straight 
and the lobes acute; —s yellow; achenes about 2 mm. long, striate -nerved, Be ae trans- 
banal rugose- Seabee s on nerves and intervals, not strongly flattened on the 
mmon —~ pes roadside weed throughout the Pacific States and across the continent. Matte of Europe 
SpringsAnteane 
3. Sonchus tenérrimus L. Slender Sow-thistle. Fig. 6024. 
Sonchus tenerrimus L. Sp. Pl. 794. 1753. 
Sonchus tenuifolius Nutt. Trans. Amer. Phil. Soc. II. 7: 438. 1841. 
Plants rather slender, leafy-stemmed to the inflorescence, glabrous, 3-8 dm. high. Leaves ob- 
long in stad eg deeply divided into several pairs of aie Spreading lobes, hee entire or denticu- 
ate, the au ricles narrow, lanceolate to ovate, sometim uate ; Pate it cea — rt corymb, 
mostly with few heads ; " phyitairies “sergbinngee age 81: fica site thic a ietow age; ligules 
yellow; achenes narrowly ovoid, 2. mm. long, = little eae longitudiealty striate and 
finely and distinctly rugose on both s striae ary intervals. 
Introduced from Europe, sandy and rocky soil; Aapecas oso the Channel _—, Santa Barbara County, 
south e western San Diego County, California, s outh to Lower California. March— Jun 
4. Sonchus asper (L.) Hill. Prickly Sow-thistle. Fig. 6025. 
Sonchus oleraceus var. asper L. Sp. Pl. 794. 1753. 
Sonchus asper Hill, Sebastian Brit. 1: 47. 1769 
Similar to Sonchus oleraceus but stems usually movies. ferdat ed angled, and more leafy. 
Leaves undivided, lobed or sometimes pinnatifid, the margin nulose-dentate or spinulose-den- 
ticulate, the low wer and basal obovate to spatulate and petioled, t the. upper oblong or lanceolate and 
clasping by an auriculate base, the auricles helicoid and appressed to the stem, the lobes ype 
ligules jonas achenes 2.5-3 mm. long, st ronely usually 3-ribbed on each face, not at all t 
versely rugose, the this, sine like a corte rrulate. 
A fairly common field and roadside weed in the ech States and also across the continent. Naturalized from 
Europe. June—Nov 
171. LACTUCA [Tourn.] L. Sp. Pl. 795. 1753. 
Leafy-stemmed annual or perennial herbs, glabrous or nearly so. Leaves linear and 
entire to broader and pinnatifid. Heads 5-56-flowered ; ligules yellow or blue, in small or 
medium-sized, paniculate heads. Involucre cylindrical, the phyllaries usually imbricated 
in several series. Receptacle flat, naked. Ligules truncate, 5-toothed at the apex enes 
oval, oblong, or linear, flattened, ribbed on each face, abruptly or gradually beaked. Pappu 
ious, of soft capillary bristles. [The ancient Latin name, from lac, milk, referring to 
the milky juice.] 
