1016 CICHORIACEAE 



b Pappus persistent, tardily falling off, separately, or together only by 



the breaking off of the beak. 

 Beak of the achenes none or a mere attenuation. 

 Flowers rose or purphsh. 



Plants spuiy and rush-like; leaves scale-like; achenes truncate at 

 the summit. 16. Pleiacanthus. 



Plants not spiny. 



Stems rush-like and striate; leai^es narrowly linear-lanceolate 



or reduced: achenes tapering at the summit. 



17. Lygodesmia. 



Stems not rush-like; leaves ample; achenes tapering to the base. 

 Annuals ; heads 4-5-flowered ; achenes with 4-5 strong ribs. 



18. Pren.anthella. 

 Perennials ; heads 8-30-flowered (rarely less) ; achenes 



terete or 4-5-angled. 19. Nab ALUS. 



Flowers yellow or white. 



Heads several, rarely solitary; stem leafy. 

 Achenes tapering upwards; jjappus wliite. 



Achenes not dilated into a pappiferous disk. 



Bracts in fruit more or less tliickened at the base or 



on the midrib. 20. Crepis. 



Bracts not thickened on the backs. 



21. Heteropleitra. 



Achenes contracted into a more or less distinct beak, 

 enlarged at the apex into a pappiferous disk. 



12. Youngia. 

 Achenes not tapering upwards; pappus in ours sordid or 



reddish; bracts not thickened. 

 Leaves simple and entire-margined or denticulate; inflor- 

 escence in ours more or less corymbiform; bracts 

 narrow, green. 22. Hieracixjm. 



Leaves divided or lobed; inflorescence thyrsoid-panicu- 

 • late; bracts broad and colored. 19. Nabalus, 



Heads solitary on a leafless scape. 10. Nothocalats. 



Beaks of the achenes distinct and slender; plants scapiferous. 



Achenes 10-ribbed or lO-nerved, not spinose-miiricate; involucres 



more or less imbricate. 23. Agoseris. 



Achenes -1-5-ribbed, muricate-spinulose at least near the apex; in- 

 volucres of a single series of principal bracts and several or num- 

 erous calyculate ones below. 24. Leontodox. 

 2. Achenes flattened; leafy-stemmed plants with paniculate heads. 



Achenes narrowed at the top or beaked; pappus- bristles falling separately; 



involucres cj lindraceous. 25. Lactuca. 



Achene trimcate at the top; pappus-bristles falling off more or less in con- 

 nection; involucres hemispherical or campanulate. 26. Soxciius. 



1. ATRICHOSERIS A. Gray, 



Glabrous winter annuals of desert regions, acaulescent, with cymoselv 

 branched scapes. Involucre of about 15 linear, acute bracts in a single series, 

 and several small calyculate ones at the base. Receptacle scrobiculate. Flowers 

 white or purplish; ligules 5-toothed at the truncate apex, Achenes oblong, with 

 corky -thickened pericarp, 8-10-ribbed, the alternate ribs thicker. Pappus none. 



1. A. platjrphylla A. Gray, Leaves rcsulate-tafted at the base, sessile, 

 rounded-obovatc, denticulate, with callous or spinulose teeth, 4-10 cm. long; 

 scape 3-6 dm. high, paniculately branched, with small bracts; involucres turbin- 

 ate, 6-8 mm. high; corollas white, with a purple base; ligules 10-12 mm. long. 

 Gravelly deserts: s Calif. — s Utah — w Ariz. Ap-Je. 



2. PTILOCALAIS Greene. 



Perennial herbs, with fusiform roots. Heads solitarv at the end of the branches. 

 Involucres cylmdnc, of ^12 bracts, in 1 or 2 series, and a few small calyculate 

 ones at the base. Receptacle with narrow scarious paleae. Corollas vellow. 

 Achenes 8-10-ribbed, columnar, Imear, trimcate at the apex. Pappus of"' 15-20 

 white soft plumose bristles with paleaceous bases. 



Pappus-squamellae oblanceplate or oblong, truncate or abruptly contracted into the awn. 

 Leaves entu^ or with short lobes. 



Leaf-blades proper lanceolate or elliptic; heads about 2.5 cm. b— ^ 

 Leaf-blades proper linear or linear-lanceolate: ]iAaH« i^c^ f>no« o 



1. P. major. 



Leaves with long filiform lobes. §; ^; ^/S&«. 



