coMrosiT^. (composite family.) 



185 



Achenia not ribbed, 5-angled. No. 



Receptacle conical CONOCLINIDM. 14 



Receptacle flat. Stems climbing. MIKANIA. 13 



Receptacle flat. Stems erect EUPATORIUM. 12 



Pappus scaly. 



Flowers blue or purple. 



Pappus a cup-shaped border of united scales CCELESTINA. 5 



Pappus slender, almost bristly. 



Pappus deciduous. Heads large and single STOKESIA. 2 



Pappus persistent. Heads small, in .3bracted clusters. . ELEPHANTOPUS. 3 



Pappus of 5 oval almost bony scales. Leaves whorled. . . SCLEROLEPIS. 7 

 Flowers white. 

 Receptacle naked. 



Leaves entire, linear or lanceolate PALAFOXIA. 57 



Leaves entire, ovate or cordate AGERATUM. 6 



Leaves pinnately lobed IIYINIENOPAPPUS. 58 



Receptacle chaffy. 



Achenium top-shaped. Scales of the pappus 5 - 6. . . . M.\RSHALLIA. 63 



Achenium flat. Pappus 2-awned. ACTINOMERIS. 49 



Flowers yellow. Pappus 2 - 4-awned. 



Awns of the pappus deciduous HELIANTHUS. 47 



Awns of the pappus persistent, hispid upward. .... COREOPSIS 50 



Awns of the pappus persistent, hispid downward EIDENS. 52 



* * Heads with flowers variously imperfect. 

 Marginal flowers pistillate. Central flowers perfect. 

 Pappus bristly. 



Scales of the involucre in a single row. ERECHTHITES. 72 



Scales of the involucre in 2 or more rows. 



Involucre persistent. Leaves sinuafe-lobed. COXYZA. 26 



Involucre persistent. Leaves entire. Anthers tailed. . . . PLUCHEA. 28 



Involucre persistent. Leaves entire Anthers tailless. . . GNAPILiLIUM. 70 



Involucre deciduous. Heads spiked PTEKOCAULON. 29 



Pappus not bristly, 5-lobed TANACETUM. 67 



Pappus none ARTEMISIA. 68 



Marginal flowers pistillate. Central flowers staminate. 



Pappus none. Style rigid, persistent. SOLIVA. 69 



Pappus none. Style deciduous. Heads nodding IVA. 35 



Marginal flowers neutral. Central flowers perfect. .... CENTAUREA. 77 



* # * Heads dioecious or moccecious. 



Staminate and pistillate heads on the same plant. 



Fruiting involucre 1-seeded, naked or tubercled AMBROSIA. 33 



Fruiting involucre 2-seeded, armed with hooked spine.s. . . . XANTHIUM. 37 



Staminate and pistillate heads on separate plants. 



Anthers tailed. Hoary herbs ANTENNARIA. 71 



Anthers tailless. Smooth shrubs BACCH.\RIS. 27 



i 2. Heads radiate. 

 Rays pistillate. 

 Flowers all fertile. 

 Receptacle naked. 



Rays yellow. Leaves opposite. 



Pappus none FLAVERIA. 55 



Pappus scaly PECTIS. 4 



Rays yellow. Leaves alternate. 



Scales of the involucre in 1 row SENECIO. 74 



Scales of the Involucre in 2 rows. IIELENIUM. 69 



Scales of the involucre in severa! rows INUL.\. 25 



