COMPOSITAE (COMPOSITE FAMILY) 



777 



Flowers purple 



Flowers whitish. 



Involucral bracts much imbricated ; leaves chielly 



opposite 



Involucral bracts little imbricated ; leaves alternate . 

 Pappus not composed of bristles e. 

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



Heads 1-flowered, themselves aggregated into globose glouierules ; 



leaves prickly 



Heads many-flowered ; leaves not prickly. 

 Outer involucre foliaceous ; leaves opposite at least below . 

 Outer involucre not foliaceous ; leaves alternate. 



Receptacle conical, becoming elongated 



Receptacle flattish or merely convex. 

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



Heads corymbose 



Pappus present/." 



/. Pappus composed of scales or chaff. 

 Receptacle naked. 



Leaves in whorls 



Leaves alternate. 



Leaves dissected' 



Leaves entire 



Receptacle bearing chaff among the 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 



obcoin pressed 



Pappus not barbed 



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



Marginal flowers neutral and sterile, either conspicuous or inconspicuous. 

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

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

 Marginal flowers pistillate and fertile h. 

 Receptacle chaft'y. 



Receptacle awl-shaped ; achenes terete 



Receptacle flattish or moderately convex ; achenes flattened . 

 Receptacle naked or bearing no conspicuous chaff *. 

 i. Pappus of capillary bristles j. 

 j. Involucral bracts imbricated in several rows. 



Leaves toothed ; not woolly 



Leaves entire ; plant 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 short 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 



7. BrickelMa. 



78. Cacalia. 



81. Echinops. 

 33. Polymnia. 



69. Matricaria. 



73. Artemisia. 



70. Chrysanthemum, 



3. Sclerolepis. 



61. Hymenopappus. 



62. Polypteris. 



65. Gaillardia. 

 58. Marshallia. 



10. Grindelia. 



53. Verbesina. 



55. Thelesperma. 



56. Bidens. 



54. Coreopsis. 



87. Cnicus. 

 86. Centaurea. 



27. Gifola. 

 51. Helianthus. 



26. Pluchea. 



29. Anaphalis. 

 80. Gnaphalium. 



75. Petasites. 



23. Erigeron. 



77. Erechtites. 



32. Adenocaulon. 



71. Tanacefurn. 



72. Cotula. 



39. Iva. 



73. Artemisia. 



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

 Pappus capillary. 

 Leaves prickly ; heads large ......... S3. Cirsium. 



Leaves not prickly ; heads small. 

 Shrubs ; leaves mostly toothed 



25. Baccharis. 



Herbs ; leaves entire. 

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



lary and slightly connate at base in the fertile . . .28. Antennaria. 

 Pappus-bristles all capillary, not at all connate . . . .29. Anaphalis. 

 Pappus none ; fertile involucre becoming bur-like. 

 Bracts of the staminate involucre united into a cup. 

 Fertile involucre armed with one ring of spines, teeth, or blunt 



processes ........... 40. Ambrosia. 



