. (COMPOSITE FAMILY.) 259 



19. C. rosea, Nutt. Smooth; stein low, branching; leaves opposite, 

 linear; heads small; rays slightly 3-tootlied ; achenia wingless, uuawned. 

 Swamps, Georgia (Xuttull), aiid northward. July -August. Stem 8' -12' 

 high. Kays rose-color. 



61. COSMOS, Cav. 



Scales of the involucre more or less united. Achenia terete or 4-angled, nar- 

 rowed or beaked at the apex, and crowned with 2-4 downwardly barbed or 

 hispid deciduous awns. Otherwise like Coreopsis. Leaves opposite, piu- 

 nately divided. Disk yellow. Hays purplish. 



1. C. caudatus, Kunth. Smooth; leaves bipiimately divided, with the 

 divisions lanceolate and entire; achenia (!' long) tapering into a very long 

 rough beak, 2-awned ; rays short, 3-cleft, rose-color. Key West, Florida. 



62. BIDENS, L. BEGGAR-TICKS. 



Chieflv like Coreopsis ; but the exterior involucre often long and leaf-like; 

 the achenia compressed, or 3 - 4-angled, (not narrowed at the apex,) and 

 crowned with 2-4 persistent downwardly barbed or hispid awns. Leaves 

 serrate, or piunately divided, opposite. Kays yellow or white, often wanting. 



Disk yellow. 



* Achenia flattened, narrowly wedge-shaped. 



1. B. frondosa, L. Stem tall, branched ; leaves thin, loiig-petioled, pin- 

 natelv 3 -5 divided; the divisions ovate or ovate-lanceolate, acuminate, 

 sharplv serrate ; heads discoid ; exterior scales of the involucre large, leafy ; 

 achenia 2-awned. Low ground. July -Sept. (T) Stem 2 -5 high. 

 Margins of th" achenia upwardly ciliate. 



2. B. connata, Muhl. Stem low, branched ; leaves oblong-lanceolate, 

 acuminate, coarsely serrate, tapering and connate at the base, the lowest often 

 3-parted ; heads discoid ; exterior involucre leafy ; achenia 2 - 4-awned, with 

 downwardly hispid margins. Western districts of Georgia and westward, 

 in damp soil. July - Sept. (T) Stem 1 - 2 high. 



3 B. cernua, L. Stem simple or branched ; leaves lanceolate, sharply 

 serrate, clasping or connate at the base, 3'- 5' long; heads nodding; outer 

 involucre leafy, usually 2-3 times longer than the inner one; rays short or 

 none ; achenia 4-awned. Wet ground in the upper districts. July - Sept. 



4. B. chrysanthemoides, Michx. Smooth; stem erect or ascending ; 

 leaves undivided, oblong-lanceolate, obscurely serrate, connate ; heads radiate, 

 showy; achenia 2 -4-awned. Wet places. Sept. -Oct. @ Stem thick, 

 l-2 high. 



* * Achenia 3 4-angled, linear: fitads radiate: scales of the involucre nearly 



cr/ual. 



5. B. leucantha, Willd. Stem low, 4-angled ; leaves pinnately divided ; 

 the divisions ovate or lanceolate, serrate ; the lowest leaves undivided ; outer 

 scales of the involucre obtuse, spreading ; the inner ones acute ; rays 5, white ; 

 achenia 2 -4-awned. South Florida Oct. - Dec. Stem 10'- 15 ' high. 



6. B. bipinnata, L. Stem tall, 4-angled, much branched ; leaves hipin- 

 nate, the divisions small, ovate or lanceolate, acute ; heads small ; ravs 2 - 3, 

 yellow; achenia 3 -4-awned. Cultivated grounds, common. Aug. -Sept. 

 (\) Stem 2 - 5 high. 



