ANALYTICAL KEY TO GENERA OF COMPOSITAE. IO41 



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hh Involucral bracts separate; style-branches of the disk-flowers 



very short Pedis 1012 



gg Plants not dotted with oil-glands. 

 h Rays rounded and nearly or quite entire at the apex. 

 i Perennial herbs or shrubs; disk-flowers all or nearly all fertile. 



Gutierrezia 927 



ii Annual herbs; disk-flowers sterile Amphiachyris 928 



hh Rays truncate and coarsely toothed or lobed at the apex. 

 * Involucral bracts spreading or reflexed. 



; Receptacle usually bristly Gaillardia 101 1 



jj Receptacle naked Helenium 1010 



ii Involucral bracts appressed or erect. 

 j Rays persistent; achenes linear, striate. 



P silo strophe 1005 

 jj Rays deciduous. 



k Achenes 4-angled, linear or oblong Picradeniopsis 1008 



kk Achenes 5-10-ribbed or 5-10-angled, top-shaped. 

 / Outer involucre bracts separate. 



Tetraneuris {Actinella, Picradenia) 1008 

 // Outer involucre bracts connate at the base. 



Picradenia {Actinella) 1009 

 ddd Pappus none or a mere crown. 

 e Receptacle not chaffy. 

 / Rays yellow. 



g Leaves pinnately divided or compound Tanacetum 10 16 



gg Leaves serrate or entire Flaveria 1006 



// Rays white or purple. 



g Rays narrow-linear, numerous, 30 or more; leaves not divided. 

 h Outer involucral bracts shorter than the inner; achenes prismatic. 



Aphanostephus 943 



hh Outer bracts all about equal; achenes flattened Bellis 943 



gg Rays broader, fewer than 30; leaves frequently divided. 

 h Receptacle flat or convex; involucral bracts in several series. 



Chrysanthemum 1014 



hh Receptacle ovoid-conic; bracts in few series Matricaria 1015 



ee Receptacle chaffy. 

 / Rays white or purple. 

 g Involucral bracts of 2 sorts. 

 h Inner bracts hooded, embracing the ray -achenes . . . .Melampodium 980 



hh Inner bracts flat, not embracing the ray -achenes Coreopsis 997 



gg Involucral bracts similar. 



h Heads very large, 5-15-cm. broad Brauneria {Echinacea) 989 



hh Heads smaller, 4 cm. broad or less. 



i Leaves opposite Eclipta 984 



ii Leaves alternate. 



j Achenes flattened; heads small Achillea 1013 



jj Achenes terete; heads large Anthemis 1014 



// Ravs yellow. 

 g Ray-flowers neutral. 



h Involucral bracts of 2 sorts Coreopsis 997 



hh Involucral bracts similar, the outer often shorter. 



i Achenes 4-angled Rudbeckia 985 



ii Achenes compressed, winged Ratibida {Lepachys) 988 



gg Ray-flowers pistillate. 

 h Achenes flattened. 



i Rays in 2-3 series; achenes falling free Silphium 980 



ii Rays in 1 series; achenes attached to 2 or 3 scales of the receptacle. 



j Leaves opposite and basal Chrysogonum 98 2 



jj Leaves alternate. 

 k Pappus none or of 2 caducous awns. . . Berlandiera 982 



