350 



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. 89. Achlllea. 



Achenes terete; involucre hemispheric; heads large. 90. Anthemis. 



** 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. 



91. Chrysanthemum. 



92. Mairicaria. 



93. Tanacetum. 



94. Artemisia. 



Tribe 8. SENECIONEAE. 



Leaves all basal ; heads on scapes. 



Heads solitary ; flowers yellow. 95. Tussilago. 



Heads corymbed ; flowers white or purple. 96. Petasites. 



Leaves opposite ; rays yellow. 



Involucre of several thin herbaceous bracts. 97. Arnica. . 



Involucre of 4 or 5 broad fleshy bracts. 98. Haploesthes. 



Leaves alternate. 



Flowers white, whitish or pinkish ; rays none. 



Marginal flowers pistillate ; disk-flowers perfect. 99. Erechtites. 



Flowers all perfect. 



Involucre of about 5 bracts; sap milky. 100. Mesadenia. 



Involucre of about 12 bracts and several smaller outer ones. 101. Synosma. 



Flowers yellow; ray-flowers mostly present. 102. 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. Centaurea. 



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,mertous 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 in 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. 



