236 COMPOSITE. (COMPOSITE FAMILY.) 



involucre oblong-linear ; rays wedge-shaped, palmately 3-lobed ; ovary wingless, 

 with hispid margins. River-banks, South Carolina and Georgia. September. 

 Stem 2 -3 high. 



---- Rays purple or rose-color. 



16. C. nudata, Nutt. Smooth ; stem slender, forking above ; leaves al- 

 ternate, distant, terete, and* rush-like ; rays bright purple, 3-toothed ; achenia with 

 lacerated wings, 2-awned. Pine-barren ponds, Florida and Georgia, near the 

 coast. April. Stem 2 high. Lowest leaves 1 long. Rays 1' long. 



17. C. rosea, Nutt. Smooth; stem low, branching; leaves opposite, lin- 

 ear ; heads small ; rays slightly 3-toothed ; achenia wingless, unawned. 

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

 high. Rays rose-color. 



18. C. CEmleri, Ell. Leaves broad-lanceolate, sessile, acute at each end, 

 entire ; peduncles axillary and terminal, dichotomously corymbose. Collected 

 near the junction of the Broad and Saluda Rivers by Mr. GEmler. Elliott. 

 Stem 2 - 3 high, angular, smooth. Leaves connate by a smaH membrane. 

 Heads small. Rays about 8, entire. Achenia wedge-shaped, slightly 2-toothed 

 and margined. ( * ) 



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, pinnately 

 divided. Disk yellow. Rays purplish. 



1. C. caudatus, Kunth. Smooth ; leaves bipinnately 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. 



52. 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 - 5-divided ; the divisions ovate or ovate-lanceolate, acuminate, sharply 

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

 2-awned. Low ground, Florida and northward. July -Sept. 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, 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. Stem 1 - 2 high. 



