5228 THE FLORA. 



3. BI'DENS. Burr-Marigold. 



Involacre scales nearly equal, double, the outer generally large and 

 leafy. Eays few (3-8, or sometimes none), neutral, disk perfect. Kecep- 

 tacle chaffy, flat. Achenia flattened or 4-sided, crowned with 2-4 awns 

 which are hispid backwards. — Leaves opposite. July-Oct. 



* Eays inconspicuous or none a 



* Buys quite showy, yellow 4, 5 



a Achenia flattened, broadest at top. . . .1-3 

 a Achenia slender, 4-sided. . . .6, 7 



1 B. frondo'sa. Leafy B. Leaves pinnately 3-5-fol., divisions distinct. Eays 0. 



2 B. conna-'ta. Leaves simple, lower ones sometimes 3-parted. Eays 0. 



3 B. cer'nua. Nodding B. Leaves simple, scarcely connate. Eays few or 0. 



4 B. clirysanthemoi''des. Mud, B. Lvs. narrow-lance., equally serrate, connate. 



5 B. Beck'ii. BecTc's B. Lvs. mostly under water and very finely divided. M. 



6 B. leucan'tha. White B. Heads small, with white rays. Lvs. pinnate. S. 



7 B. bipinna'ta. Spanish Needles. Eays very short, yellow. Lvs. bi-pinnate. 



4. COREOP'SIS. Tick-seed. 



Involucre many-flowered, double, each of 8-13 scales, the outer leafy, 

 the inner membranous. Receptacle flat, the chaff falling with the fruit. 

 Achenia flattened, often winged, emarginate, each commonly with 2 teeth 

 or awns which are not hispid downwardly as in Bidens. — Leaves gener- 

 ally opposite. Heads showy (rarely without rays). 



* Heads discoid (without rays) 1,2 



* Heads radiate, rays showy a 



a Disk yellow, rays also yellow, mostly entire b 



a Disk yellow, rays rose-colored, 3-5-toothed at the end 20, 21 



a Disk purple, rays yellow with a purple base, toothed. . . .18, 19 

 a Disk purple, rays wholly yellow, toothed at the end. . . .14-17 



b Leaves petiolate, compound, with lanceolate, toothed divisions 3-5 



b Leaves petiolate, compound, with linear, entire divisions.. . .6, 7 



b Leaves petiolate, simple, or some of them eared at base 8-10 



b Leaves sessile, 3-parted, divisions entire or not often, seeming whorled 11-13 



1 C. discoi''dea. Mayless T. Leaves on long petioles, ternately divided. "W. 



2 C. bidentoi'des. Leaves on short petioles, toothed, lance-linear. Penn. r. 



8 O. au'rea. Golden T. Leaflets 3-5. Outer scales about 8. Achenia 2-4-toothed. S. 



4 C. trichosper'ma. Leaflets 5-7. Outer scales about 8. Ach. slender, 2-toothed. 



5 C. aristo'sa. Leaflets 5-7. Outer scales 10-13. Achenia 2 or 4-awned. W. 



6 C. trip'teris. Stem 4-8f. high. Hds. on short stalks. Eays 2' long, entire. W. S 



7 O. grandiflo'ra. St. l-2f. high. Heads on long stalks. Enys 1' long, 4-5-oleffe. 8 



