SUNFLOWER FAMILY. 405 



Flowers yellow; receptacle with chaff-like bracts; thistle-like plant 2. Scolymis. 



Pappus consisting of bristles, the bristles (or some of them) plumose. 

 Receptacle naked. 



Achenes not beaked nor ribbed; tall annuals, paniculately branching above 



3. Steph womkkia. 

 Achenes (at least the inner) with a slender beak. 



Flowers yellow; achenes 5 to 10-ribbed; low branching thistle-like biennial 



4. PlCRIS. 



Flowers purple; achenes ribbed; perennial or biennial with grass-like leaves 



5. Tragopogon. 



Flowers white; achenes obscurely ribbed; stem branching above; annual 



6. Rafinesquia. 

 Receptacle with chaff-like bracts; at least the inner achenes beaked; flowers yellow; 



stems naked; leaves radical 7. Hypochaeris. 



Pappus paleaceous, the paleaceous portion short or often very long, tipped with a long 



or short bristle or awn which is either naked or barbellate, or rarely subplumose; 



achenes not beaked. 



Ligules short, the head in anthesis small; bracts of the involucre equal but with 



shorter ones at base, all membranous; pappus-bristles 5. 



Paleae of the pappus elongated, cleft at tip, the short bristle or awn proceeding from 



the cleft; peduncle enlarged at summit; heads erect 8. Uropappus. 



Paleae of the pappus mostly short, abruptly or gradually passing into the awn; 



peduncles not enlarged at summit; heads nodding in the bud 9. Microseris. 



Ligules elongated, the heads in anthesis showy; bracts of the involucre imbricated in 

 several series; pappus-bristles 10 or more, barbellate or subplumose, the paleaceous 



base short and firm 10. Scorzoxella. 



B. Pappus of fine soft capillary bristles, scabrous but never plumose; achenes ribbed 



or nerved. 

 Achenes not flattened; receptacle naked, or bristly in some species of no. 11. 

 Achenes beakless; stems commonly branching or the plants acaulescent. 



Pappus mostly soft and deciduous; achenes terete, truncate 11. Malacothrix. 



Pappus dull white or tawny; achenes linear 12. Hieracium. 



Pappus white; achenes columnar or fusiform 13. Crepis. 



Achenes with a slender beak; acaulescent plants, the peduncles 1-flowered. . 14. Agoseris. 

 Achenes flattened; receptacle naked; leafy-stemmed plants. 



Achenes beaked; heads in a panicle 15. Lactuca. 



Achenes not beaked; heads corymbed or umbellate 16. Soxchus. 



Tribe 2. Cynareae. Thistle Tribe. 



Thistles or thistle-like herbs with alternate prickly leaves. Heads large. 

 Bracts of the involucre imbricated, usually prolonged into a spine or bristle, 

 or provided with a membranous edge. Eeceptacle bristly or hairy. Flowers all 

 perfect. Eays none. Corollas tubular, cleft into long narrow lobes. Anthers 

 long-tailed at the base, with elongated appendages at the tip. Pappus bristly 

 or plumose, rarely paleaceous. 



A. Achenes obliquely or somezchat laterally inserted on the receptacle. 



Heads not leafy-involucrate; pappus-bristles or -scales in 2 or 3 rows or none 



17. Cextaurea. 



Heads leafy-involucrate; pappus-awns in 2 series 18. Cxicus. 



B. Achenes inserted on the receptacle by their very base. 

 Filaments distinct. 



Pappus paleaceous and double (in 2 different sets) 19. Carthamus. 



Pappus of plumose bristles, united at base and deciduous in a ring. 



Bristles of the pappus in several series; achenes somewhat 4-angled 20. Cyxara. 



Bristles of the pappus in a single series; achenes not angled 21. Cirsilm. 



Filaments united below; pappus of narrow barbellate paleae 22. Silybum. 



Tribe 3. Senecioneae. Groundsel Tribe. 



Herbs, or two species suffrutescent. Leaves alternate or radical. Bracts 

 of the involucre little or not at all imbricated, mostly in 1 or 2 rows. Eecep- 

 tacle naked. Flowers of both disk and ray yellow, except Petasites. An- 

 thers not caudate. Pappus-bristles soft, commonly copious, most often white. 



