274 CICHORIACEAE 



Achenes 5-ribbed; main bracts scarious-margined ; reoeptacia 



bristly. 11. Calycoseris. 



Achenes 10-striate; bracts not scarious: receptacle not bristly. 



12. YOUNGIA. 

 Achenes S-ribbed, conspicuously cancellate-sculptured, with a cupu- 

 late shoulder, from which the slender, 5-ribbed hollow beak 

 arises. 13. Gltptoplura. 



Achenes not beaked, columnar, 5-15-ribbed, truncate at the apex. 

 Involucres of broad silvery-scarious bracts, regularly imbricate: 



bristles of the receptacle persistent. 14. Malacolepis. 



Involucres of narrow acuminate or acute bracts, only slightly scari- 

 ous-margined; bristles of the receptacle, if any, few and decidu- 

 ous. 15. Malacothrix. 

 6. 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 purplish. 



Plants spiny and rush-like: leaves scale-like; achenes truncate at 

 the summit. 16. Pi.eiacantbits. 



Plants not spiny. 



Stemfi rush-like and striate; leaves narrowly llnear-lcincetdate 

 or reduced; achenes tapering a.t 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. Pbenanthella. 

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



terete or 4-5-angled. 19. Nabalus. 



Flowers yellow or white. 



Heads several, rarely soUtary; stem leafy. 

 Achenes tapering upwards; pappus white. 



Achenes not dilated into a pappiferous disk. 



Bracts in frulb more or less thickened at the base or 



on the midrib. 20. Crepis. 



Bracts not thickened on the backs. 



21. Heteropi^ura 

 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. Hieracium. 



Leaves divided or lobed; inflorescence thyrsoid-i>anicu- 

 late; bracts broad and colored. 19. Nabalus. 

 Heads solitary on a leafless scape. 10. Nothocalais. 



Beaks of the achenes distinct and slender; plants scapiferous. 



Achenes 10-rlbbed or 10-nerved, not spinose-muricate; involucres 



more or less imbricate. 23. Agoseris. 



Achenes 4-S-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. Leontodon. 

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



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



involucres cylindraceous. 25. Lactuca. 



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

 nection ; involucres hemispherical or campanulate. 26. Sonchus. 



1. ATRICHOSKRIS A. Gray. l. A. platyphylla. 



2. PTILOCALAIS Greene. 



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

 Leaves entire or with short lobes. 



Leaf-blades proper lanceolate or eUiptic; heads about 2.5 cm. high. 



1. P. major. 

 Leaf-blades proper linear or linear-lanceolate; heads less than 2 cm. high. 



2. P. nutans. 

 Leaves with long filiform lobes. 3. P. graciloba. 



Pappus-squamellae Unear-lanceolate, gradually tapering into the awn. 



Leaves linear-lanceolate or lanceolate; squamellae 4-5 mm. long. 4. P. macrolepis. 

 Leaves narrowly linear; squamellae 2 mm. long or less. 5. P. tenuifolia. 



3. PTILORIA Raf. Desert Pink, Flowering Straw. 



Perennials. 



Heads 10-20-flowered ; involucres over 1 cm. high; leaves broad, runcinate, with short 



lobes. 1. P. Parryi. 



Heads 3-9- (mostly 5-) flowered. 



Pappus plumose to the base; involucres 7-10 mm. high. 



Leaves very narrow, almost filiform and usually entire. 2. P. tenuifolia. 



