412 ASTERACEAE. 



and yellow flowers in corymbose or paniculate heads. 

 Involucre usually becoming thickened and more or less 

 conic at base, its bracts imbricated in several series, the 

 outer successively smaller. Receptacle flat, naked. 

 Achenes flattened, 10-20-ribbed, truncate. Pappus of 

 copious soft white simple capillary bristles usually falling 

 away connected. 



1. S. oleraceus L. Stoutish, 5-10 dm. high, sparingly leafy, 

 glabrous or with a few glandular hairs on the pedicels and involucre, 

 glaucescent; leaves obovoid or narrower, runcinate-pinnatifid, 

 toothed but not prickly-margined, amplexicaul, the auricles straight, 

 acute; achenes striate-nerved, transversely rugulose-scabrous. 



Common everywhere, flowering at all seasons. Native of Europe. 



2. S. asper (L.) All. Stouter than the last, the stems distinctly 

 angled, very leafy; leaves entire or pinnatifid, prickly-margined, 

 the auricles helicoid and appressed to the stem; achenes 3-nerved on 

 each side, otherwise smooth. 



A less common weed than the last. Native of Europe. 



80. LACTUCA L. 



Tall leafy herbs with small panicled heads. Involu- 

 cre cylindric, its bracts imbricated in several series, the 

 outer shorter. Receptacle flat, naked. Achenes flat- 

 tened, 6-10-ribbed, beaked. Pappus of copious white or 

 brownish capillary bristles. 



1. L. virosa L. Biennial, glaucous; stems leafy, paniculately 

 branched, hirsute at the base or glabrous throughout, 6-18 dm. 

 high; leaves oblong to oblong-lanceolate, spinulose-margined, 

 denticulate or pinnatifid, sessile or auriculate-clasping, midrib 

 spinulose or hispid; heads 4-8 mm. broad, 6-12-flowered, very 

 numerous, in an open panicle; involucre cylindric; ligules yellow; 

 achenes obovate-oblong, about equaling the filiform beak; pappus 

 white. (L. scariola L.) 



Rather common in streets about Los Angeles. Native of Europe. 



81. AGOSERIS Raf. 



Perennial or annual herbs, mostly acaulescent, with 

 tufted basal leaves, and solitary heads of yellow or rarely 

 purple flowers at the ends of naked or bracted scapes. 

 Involucre campanulate to oblong, its bracts imbricated 

 in several series. Receptacle flat, naked or faveolate. 

 Achenes not flattened, 10-ribbed, beaked at the summit. 

 Pappus of copious slender simple white bristles. 



