778 COMPOSITAE (COMPOSITE FAMILY) 



Fertile involuere 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. Hays 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 I. 



I. Kays occupying several rows. 



Kays yellow 74. Tuwilago. 



Rays white or purplish. 



Leaves cordate 75. Petasites. 



Leaves not cordate 23. Erigeron. 



I. Kays in one marginal row m. 

 m. Kays 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. 



Kays 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. Chrysopsis. 



Ray -flowers with coroniform pappus 13. Heterotkeca. 



n. Pappus simple. 



Leaves opposite 76. Arnica. 



Leaves alternate. 



Involucral bracts equal and in 1 row (though often calyculate) . 79. Senecio. 

 Involucral bracts imbricated in several series. 



Heads 3-5 cm. in diameter 31. Inula. 



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. Gutierrezia. 



Pappus-bristles hair-like. 

 Pappus- 



'appus-bristles equal 15. Solidago. 



Pappus-bristles unequal 17. Aplopappus. 



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

 flowers 10. Grindelia. 



* * * Pappus a circle of chaffy scales dissected into bristles . . 66. Dyssodia. 

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



o. Receptacle deeply honeycombed 57. Balduina. 



o. Receptacle not deeply honeycombed, naked. 



Receptacle flattish ; heads small, few-flowered. 

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



Leaves entire, linear, never cordate 11. Gutierrezia. 



Receptacle elevated, strongly convex ; heads many-flowered. 



Scapose 63. Aetinea. 



Leafy-stemmed ; leaves decurrent 64. Helenium. 



o. Receptacle not deeply honeycombed, chaffy. 



Heads less than 1 cm. in diameter 59. Galinsoga. 



Heads more than 1 cm. in diameter 65. Gaillardia. 



***** 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. 



-t- RECEPTACLE NAKED p. 

 p. Achenes flattened. 



Achenes wing-margined ; pappus present 21. Boltonia. 



Achenes marginless ; pappus none 19. Bellis. 



p. Achenes terete or prismatic. 



Receptacle conical 69. Matricaria. 



Receptacle flattish. 



Heads very small ; ray-flowers mostly 1 60. Flaweria. 



Heads rather large ; rays numerous 70. Chrysanthemum 



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



-t- +- RECEPTACLE CHAFFY q. 



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

 and fertile. 



