[*][*] _Outer scales narrow, shorter, all united at base; rays entire, obtuse; pappus none; leaves petiolate, pinnately 3--5-divided; perennial._ 12. C. trípteris, L. (TALL COREOPSIS.) Smooth; stem simple (4--9° high), corymbed at the top; leaflets lanceolate, acute, entire.--Penn. to Wisc., Iowa, and southward. Aug.--Sept.--Heads exhaling the odor of anise when bruised; disk turning brownish. [*][*][*] _Scales mostly distinct, the outer leafy, reflexed or spreading; achenes flat, obovate or cuneate-oblong, 1-nerved on each face, 2-toothed or 2-awned (rarely 4-awned); leaves petiolate, usually pinnately 3--7-divided, the lobes serrate; annuals (or biennial), branching. Approaching_ Bidens. [+] _Rays conspicuous, golden yellow._ [++] _Achenes cuneate, obscurely ciliate or naked; outer scales about 8._ 13. C. aùrea, Ait. Nearly glabrous, 1--3° high; leaves variable, commonly 3--7-divided, or some or all undivided, the segments incisely serrate or lobed; _achenes broadly cuneate_, 1--2´´ long, with 2 _very short blunt spreading teeth_.--Wet ground, Va. to Fl. 14. C. trichospérma, Michx. (TICKSEED SUNFLOWER.) Smooth, branched; leaves short-petioled, nearly all 3--7-divided; leaflets lanceolate or linear, cut-toothed, or the upper leaves only 3--5-cleft and almost sessile; heads panicled-corymbose; _achenes narrowly wedge-oblong or the inner ones wedge-linear_, about 4´´ long, smooth or sparsely hairy, marginless, _crowned with 2 erect triangular or awl-shaped stout teeth_.--Swamps, Mass. to Va. near the coast. Also Buffalo, N. Y., to Ill., where is a var. TENUÍLOBA, Gray, with shorter achenes, approaching the last. Aug.--Oct. [++][++] _Achenes obovate, very flat, with thin ciliate margins._ 15. C. aristòsa, Michx. Somewhat pubescent; leaves 1--2-pinnately 5--7-divided, petioled; leaflets lanceolate, cut-toothed or pinnatifid; heads panicled-corymbose; outer scales 8--10, not exceeding the inner, barely ciliate; _achenes_ with 2 (rarely 4) _long and slender diverging awns_ as long as the achene itself.--Swamps, Ohio to Mich., Minn., and southwestward. Aug.--Oct.--Var. MÙTICA has two short divergent teeth or points in place of the awns.--W. Ill. and southwestward. Forms occur with the barbs of the awns spreading or retrorse, hybrids with _Bidens frondosa_ or other species. 16. C. involucràta, Nutt. Heads rather larger, the outer scales 12--20, mostly exceeding the inner, slender and hispid; achenes with 2 short acute teeth.--W. Ill. to Kan. and Tex. [+][+] _Rays none, or rarely rudimentary; outer scales usually 3--5, loose, leafy, commonly surpassing the short-pedunculate heads; achenes narrowly cuneate; plants glabrous, 1--3° high; leaves petiolate._