COMPOSIT.^. (composite FAMILY.) 259 



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

 linear; heads small; rays slightly 3-toothed ; achenia wingless, unawued. — 

 Swamps, Georgia {Nuttall), and northward. July -August. — Stem 8'- 12' 

 high. Rays 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, pin- 

 nately divided. Disk yellow. Rays purplish. 



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

 divisions lanceolate and entire; achenia (1' long) tapering into a very long 

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



62. BIDENS, L. Beggar-ticks. 

 Chiefly 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 pinnately divided, opposite. Rays yellow or white, often wanting. 

 Disk yellow. 



* Achenia flattened, narrowly wedge-shaped. 



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

 nately 3 - o-divided ; the divisions ovate or ovate-lanceolate, acuminate, 

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

 achenia 2-awned. — Low ground. July - Sept. (l) — Stem 2° - 5° high. 

 Margins of the achenia upwardly ciliate. 



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

 acuminate, coarsely serrate, tapering and connate at the base, tlie 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. Julv - Sept. 



4. B. ehrysanthemoides, 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-'i-angIed, liyiear : heads radiate: scales of the involucre nearly 



equal. 



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

 the divisions ovate or lanceolate, serrate ; the lowest leaves undi\nded ; outer 

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

 achenia 2 - 4-awned. — South Florida. Oct. - Dec. — Stem 1 0' - 1 .5 ' high. 



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

 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. 



