COMPOSITAE (COMPOSITE FAMILY) 



777 



Flowers purple 6. TrUita. 



Flowers whitish. 

 Involucral bracts much imbricated ; leaves chiefly 



opposite 7. BricktUia. 



Involucral bracts little Imbricated ; leaves alternate . 78. Cacalia. 

 a. Pappus not composed of bristles e. 



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



Heads 1-flowered, themselves aggregated into globose glomerules; 



leaves prickly 81. Echinopt. 



Heads many-flowered ; leaves not prickly. 



Outer involucre foliaceous ; leaves opposite at least below . . 33. Polymnia. 

 Outer involucre not foliaceous ; leaves alternate. 



Receptacle conical, becoming elongated 60. Matricaria. 



Receptacle flattish or merely convex. 

 Heads chiefly nodding, in" spikes, racemes, or panicles . . 78. Artemima. 



Heads corymbose 70. Chrytnnthtmum 



6. Pappus present/. 

 f. Pappus composed of scales or chaff. 

 Receptacle naked. 



Leaves in whorls 8. Sclerolepi*. 



Leaves alternate. 



Leaves dissected 61. Hymenopappus. 



Leaves entire 62. Polypteris. 



Receptacle bearing chaff among the flowers. 



Leaves toothed or lobed 66. Gaillardia. 



Leaves entire 58. Jfarnhallia. 



f. Pappus of 2 several teeth or awns. 



Pappus caducous 10. Grindtlia. 



Pappus persistent. 



Achenes laterally compressed 58. Verbesina. 



Achenes terete or flattened parallel with the Involucral bracts. 

 Pappus barbed. 



Bracts of inner involucre connate to middle ; achenes terete 55. Thtltxperma. 

 Bracts of inner involucre distinct or nearly so ; achenes 



obcompressed 56. Bidens. 



Pappus not barbed 54. Coreopsis. 



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



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



Leaves spiny ; heads subtended by foliaceous bracts . . . .87. Cnicvs. 

 Leaves not spiny ; no conspicuous foliaceous bracts . . . .86. Centaurea. 

 ff. Marginal flowers pistillate and fertile h. 

 h. Receptacle chaffy. 



Receptacle awl-shaped ; achenes terete 27. Gifola. 



Receptacle flattish or moderately convex ; achenes flattened . . 51. Ilelianthu*. 

 h. Receptacle naked or bearing no conspicuous chaff i. 

 i. Pappus of capillary bristles j. 

 j. Involufsl bracts imbricated in several rows. 



Leaves toothed ; not woolly 26. Pluchea. 



Leaves entire ; plant more or less woolly. 

 Some flowers staminat and sterile ...... 29. Anaphalit. 



. All flowers fertile, either pistillate or perfect . . . .80. Gnaphalium. 



j. Involucral bracts chiefly in one row. 



Leaves cordate, triangular or palmately lobed . . . .75. Petatite*. 



Leaves not cordate. 



Involucre campanulate 28. Erigeron. 



Involucre ovoid at base, cyllndric above 77. ErecMAtes. 



i. Pappus a short crown or none. 



Achenes becoming much longer than the involucre . . . 82. Adenocaufon. 

 Achenes not exceeding the involucre. 



Heads corymbose, erect 71. Tanacetum. 



Heads solitary on long peduncles 72. Cotvta. 



Heads racemose or paniculate, nodding. 



Lower leaves opposite 89. Ita. 



Lower leaves alternate 78. Artemisia. 



* * Staminate and pistillate flowers in separate heads k. 

 k. Pappus capillary. 



Leaves prickly ; heads large S3. Oirsivm. 



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. Anaphalts. 

 k. 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. 



