35 



COMPOSITAE. 



VOL. III. 



Outer involucral bracts connate. 83. Hymenoxys. 



Bracts of the involucre spreading, or reflexed at maturity. 84. Helenium. 



Receptacle with bristle-like chaff. 85. Galliardia. 



** Plants dotted with oil-glands, especially the leaves and involucre. 

 Involucral bracts more or less united ; style-branches of the disk-flowers elongated. 



Involucral bracts united at the base. 86. Boebera. 



Involucral bracts united high up into a cup. 87. Thymophylla. 



Involucral bracts separate ; style-branches of the disk-flowers very short. 88. Pectis. 



Tribe 7. ANTHEMIDEAE. 



* Receptacle chaffy. 



Achenes flattened ; involucre obovoid to campanulate ; heads small. 

 Achenes terete ; involucre hemispheric ; heads large. 



** Receptacle not chaffy, naked, or sometimes hairy, 

 i. Ray-flowers usually present, sometimes wanting. 

 Receptacle flat to hemispheric ; bracts of the involucre in several series. 

 Receptacle conic to ovoid ; bracts in few series. 



2. Ray-flowers none ; heads small. 



Heads corymbed ; pappus a short crown ; flowers yellow. 

 Heads racemose, spicate or panicled ; pappus none. 



Tribe 8. SENECIONEAE. 



Leaves all basal ; heads on scapes. 

 Heads solitary ; flowers yellow. 

 Heads corymbed ; flowers white or purple. 

 Leaves opposite ; rays yellow. 



Involucre of several thin herbaceous bracts. 

 Involucre of 4 or 5 broad fleshy bracts. 

 Leaves alternate. 



Flowers white, whitish or pinkish ; rays none. 



Marginal flowers pistillate ; disk-flowers perfect. 

 Flowers all perfect. 



Involucre of about 5 bracts ; sap milky. 



Involucre of about 12 bracts and several smaller outer ones. 

 Flowers yellow ; ray-flowers mostly present. 



89. Achillea. 

 go. Anthemis. 



91. Chrysanthemum, 



92. Matricaria. 



93. Tanacetum. 



94. Artemisia. 



95. Tussilago. 



96. Petasites. 



97. Arnica. . 



98. Haploesthes. 



99. Erechtites. 



100. Mesadenia. 



101. Synosma. 



1 02. Senecio. 



Tribe 9. CYNAREAE. 



* Achenes inserted on the receptacle by their bases, not oblique. 



Receptacle densely bristly. 

 Filaments separate. 



Involucral bracts hooked at the tip; leaves not bristly. 103. Arctium. 



Involucral bracts not hooked ; leaves bristly. 



Pappus-bristles plumose. 104. Cirsium. 



Pappus-bristles not plumose. 105. Carduus. 



Filaments united below. 106. Mariana. 



Receptacle fleshy, not bristly. 107. Onopordon. 



** Achenes obliquely inserted on the receptacle. 



Heads not subtended by bristly leaves; involucral bracts often bristly. 108. Centaur ea. 



Heads sessile, subtended by bristly leaves. 109. Cnicus. 



i. VERNONIA Schreb. Gen. PI. 2: 541. 1791. 



Erect branching perennial herbs, or some tropical species shrubby, with alternate (very 

 rarely oposite), in our species sessile leaves, and discoid cymose-paniculate heads of purple 

 pink or white tubular flowers. Involucre hemispheric, campanulate or oblong-cylindric, its 

 bracts imbricated in several or many series. Receptacle flat, naked. Corolla regular, S-cleft. 

 Anthers sagittate at the base, not caudate. Style-branches subulate, hispidulous their whole 

 length. Achenes 8-io-ribbed, truncate. Pappus of our species in 2 series, the inner of 

 nu,merbus roughened capillary bristles, the outer of much shorter small scales or stout 

 bristles. [Named after William Vernon, English botanist.] 



More than 500 species, of wide distribution in warm-temperate regions, most abundant ; n South 

 America. Besides the following, several others occur in the southern and southwestern United 

 States. Type species: Serratula noveboracensis L. 

 Heads large, nearly i' broad ; involucral bracts with long filiform tips. 

 Heads smaller, 6" broad or less. 



Involucral bracts with filiform tips. 



Leaves lanceolate, relatively narrow ; pappus purple, rarely green. 

 Leaves oval to lanceolate, relatively broad ; pappus yellowish. 

 Involucral bracts acute or obtuse, not filiform-tipped. 

 Leaves linear, i-nerved. 

 Leaves lanceolate to oblong-lanceolate. 



Leaves glabrous or merely puberulent beneath. 

 Heads loosely cymose. 

 Heads densely cymose. 

 Leaves tomentose beneath. 



Involucral bracts squarrose, acuminate. 

 Involucral bracts obtuse or acute, appressed. 



i . V. crinita. 



2. V . noveboracensis. 



3. V. glauca. 



4. V. marginata. 



5. V. altissima. 



6. V '. fasciculata. 



7. V. Baldwinii. 



8. V ' . missurica. 



