778 



COMPOSITAE (COMPOSITE FAMILY) 



Fertile involucre armed with 2 or more rows of spines or these 



irregularly distributed 41. Franseria. 



Bracts of staminate involucre distinct ; fertile involucre horned in 



fruit and very prickly 42. Xanthium. 



2. Rays present, i.e. the marginal flowers or some of them with strap-like 



corollas. 



* Pappus of capillary bristles, at least in the disk flowers; ray flowers pistillate 

 74. Tussilago. 



I. Rays occupying several rows. 



Rays yellow 



Rays white or purplish. 



Leaves cordate 75. Petasites. 



Leaves not cordate 23. Erigeron. 



I. Rays in one marginal row m. 

 m. Rays not yellow. 



Upper part of stem bearing ovate or lanceolate phyllodia . . . 75. Petasites. 

 Phyllodia none. 



Rays and disk-flowers similarly colored 15. Solidago. 



Rays and disk-flowers of contrasting colors. 



Rays 4 or 5 .24. Sericocarpus. 



Rays numerous. 



Involucral bracts subequal, narrow, chiefly in 1 series . . 23. Erigeron. 

 Involucral bracts imbricated in several mostly unequal series 22. Aster. 

 m. Rays yellow n. 



n. Pappus (at least in the disk-flowers) double, the outer short and 

 minute. 



Ray-flowers with pappus of capillary bristles 14. 



Ray -flowers with coroniform pappus 18. 



n. Pappus simple. 



Leaves opposite 76, 



Leaves alternate. 



Involucral bracts equal and in 1 row (though often calyculate) 

 Involucral bracts imbricated in several series. 



Heads 3-5 cm. in diameter 



Heads 2 cm. or less in diameter. 

 Pappus of several very narrow scales rather than truly 



capillary bristles. 

 Pappus of disk-flowers nearly or quite as long as the 



corolla 12. Amphiachyris. 



Pappus of disk-flowers much shorter than the corolla . 11. Gutierrezin. 

 Pappus-bristles hair-like. 



Pappus-bristles equal 15. Solidago. 



Pappus-bristles unequal 17. Aplopappus. 



* * Pappus a circle of awns or rigid bristles at least in the disk- 

 flowers . . .10. 



* * * Pappus a circle of chaffy scales dissected into bristles 

 * * * * Pappus a circle of thin chaffy scales or short chaffy bristles 



o. Receptacle deeply honeycombed 



Grindelia. 

 66. Dyssodia. 



57. Said n inn. 



Receptacle not deeply honeycombed, naked. 

 Receptacle ttattish ; ' 



heads small, few-flowered. 



Leaves serrate, the lower heart-shaped 16. BracJiychaeta. 



Leaves entire, linear, never cordate \\.jintiri-rezia. 



Receptacle elevated, strongly convex ; heads many-flowered. 



Scapose 63. Actincn. 



Leafy-stemmed ; leaves decurrent 64. Helenium. 



Receptacle not deeply honeycombed, chaffy. 

 Ilcmls less than 1 cm. in diarne 



diameter 

 Heads more than 1 cm. in diameter 



***** Pappus none, or a cup or crown, or of a or 3 awns, teeth or chaffy scales corresponding 

 with the edges or angles of the achene, often with intervening minute bristles 

 or scales. 



+- RECEPTACLE NAKED p. 

 /-. Aclienrs flattened. 



Achenes wing-margined ; pappus present 21. R/t<mi,i. 



Achenes marginless; pappus none 19. Belli*. 



p. Achenes terete or prismatic. 



Receptacle conical 69. JfafrfoOfiO, 



Receptacle flattish. 



I It 'ads very small ; ray-flowers mostly 1 60. Flarsria. 



Heads rather large; rays numerous 70. Chrysanthemum. 



p. Achenes fusiform ; pappus' of few scales, usually alternating with awns 20. 



+- -- RECEPTACLE CHAFFY </. 



q. Rays neutral (rarely pistillate but sterile); the disk-flowers perfect 

 and fertile. 



