COMPOSITAE (composite FAMILY) 



777 



a, 



Flowers purple 



Flowers whitish. 

 Involucral bracts much imbricated ; leaves chiefly 



opposite 



Involucral bracts little imbricated ; leaves alternate . 

 Pappus not composed of bristles e. 

 e. Pappus none or a mere crown-like margin to the fruit. 



Heads 1-tiowered, themselves aggregated into globose glomerules ; 



leaves prickly 



Heads many-tiowered ; leaves not prickly. 

 Outer involucre foliaceous ; leaves opposite at least below 

 Outer involucre not foliaceous ; leaves alternate. 



Keceptacle conical, becoming elongated 



Receptacle flattish or merely convex. 

 Heads chiefly nodding, in spikes, racemes, or panicles . 



Heads corymbose 



e. Pappus present/. 

 /. Pappus composed of scales or chaflf. 

 Eeceptacle naked. 



Leaves in whorls 



Leaves alternate. 



Leaves dissected 



Leaves entire 



Eeceptacle bearing chaff' among tjie flowers. 



Leaves toothed or lobed • . . 



Leaves entire 



/. Pappus of 2-several teeth or awns. 



Pappus caducous 



Pappus persistent. 



Achenes laterally compressed 



Achenes terete or flattened parallel with the involucral bracts. 

 Pappus barbed. 

 Bracts of inner involucre connate to middle ; achenes terete 

 Bracts of inner involucre distinct or nearly so ; achenes 



obcompressed ' . . . 



Pappus not barbed 



6. Th'iUsa. 



7. BrickeUia. 

 78. Cacalia. 



81. Echinops. 

 33. Polymnia. 



69. Matricaria. 



73. Artemisia. 



70. Chrysanthemum 



3. Sclerolepia. 



61. Eymenopappus. 



62. Polypteris. 



65. Gaillardia. 

 58. 3farshallia. 



* * Flowers of two kinds in the same head g. 



10. Grindelia. 



53, Verbesina. 



55. Thelesperma. 



56. Bidens. 



54. Coreopsis. 



g. Marginal flowers neutral and sterile, either conspicuous or inconspicuous. 

 Leaves spiny : heads subtended by foliaceous bracts .... 

 Leaves not spiny ; no conspicuous foliaceous bracts .... 

 g. Marginal flowers pistillate and fertile h. 

 h. Eeceptacle chafi'y. 



Eeceptacle awl-shajied ; achenes terete 



Eeceptacle flattish or moderately convex ; achenes flattened . 

 h. Receptacle naked or bearing no conspicuous chalF i. 

 i. Pappus of capillary bristles .;. 

 j. Involuf"-al bracts imbricated in several rows. 



Leaves toothed ; not woolly 



Leaves entire ; iilant more or less woolly. 

 Some flowers staminate and sterile . 

 All flowers fertile, either pistillate or perfect . 

 Involucral bracts chiefly in one row. 

 Leaves cordate, triangular or palmately lobed 

 Leaves not cordate. 



Involucre campanulate 



Involucre ovoid at base, cylindric above . 

 Pappus a .«^hort crown or none. 

 Achenes becoming much longer than the involucre 

 Achenes not exceeding the involucre. 



Heads corymbose, erect 



Heads solitary on long peduncles .... 

 Heads racemose or paniculate, nodding. 



Lower leaves opposite 



Lower leaves alternate 



87. Cnicus. • 

 86. Centaurea. 



27. Gifol<i. 



51. Helianthus. 



26. Pluchea. 



3' 



29. A naphalis. 



30. Gnaphalium, 



75. Petasiies. 



23. Erigeron. 



77. Erechtites. 



32. Adeiwcaulon. 



71. Tanacetum. 



72. Cotula. 



39. Ira. 



73. Artemisia. 



* ** Staminate and pistillate flowers in separate heads A-. 

 h. Pappus capillary. 



Leaves prickly ; heads large S3. Cirsium,. 



Leaves not iirickly ; heads small. 



Shrubs ; leaves mostly toothed 25. Baccharis. 



Herbs ; leaves entire. 



Pappus-bristles somewhat club-shaped in sterile flowers, but capil- 

 lary and slightly <'<iniiate at base in the fertile . . . 28. Antennaria. 

 Pappus-bristles ali capillary, not at all connate . . .29. AnnpJialis. 

 k. Pappus none ; fertile invuhu-n' becoming bur-like. 



Bracts of the staminate involucre united into a enp. 

 Fertile involucr*^ armed with one ring of spines, teeth, oi- blunt 



processes 4(».- Ambrosia. 



