228 THE FLORA. 
8. BI'DENS. Burr-Marigold. 
Involucre scales nearly equal, double, the outer generally large and 
leafy. Rays few (8-8, or sometimes none), neutral, disk perfect. Recep- 
tacle chaffy, flat. Achenia flattened or 4-sided, crowned with 2-4 awns 
which are hispid backwards.—Leaves opposite. July—Oct. 
* Rays inconspicuous or none....a 
* Rays quite showy, yellow....4, 5 
a Achenia flattened, broadest at top....1-8 
a Achenia slender, 4-sided....6, 7 : 
1 B. frondo’sa. Leafy B. Leaves pinnately 3-5-fol., divisions distinct. Rays 0. 
2 B.conna’ta. Leaves simple, lower ones sometimes 8-parted. Rays 0. 
8 B.cer’nua. .Vodding B. Leaves simple, scarcely connate. Rays few or 0. 
4 B. chrysanthemoi’des, Mud B. Lvs. narrow-lance., equally serrate, connate, 
5 B. Beck’ii. Beck'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, Rays 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 Bivens.—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, 8-parted, divisions entire or not often, seeming whorled....11-18 
1 ©, discoi’dea, Laylese T. Leaves on long petioles, ternately divided. W. 
2 C. bidentoi’des. Leaves on short petioles, toothed, lance-linear. Penn. 7. 
8 C. au’rea, Golden T. Lexatlets 8-5. Outer scales about 8. Achenia 2-4-toothed. 8, 
4 C.trichosper’ma. Leaflets 5-7. Outer scales about 8. Ach. slender, 2-toothed. 
6 O. aristo’sa. Leaflets 5-7. Outer scales 10-18. Achenia 2 or 4-awned. W. 
6 O. trip’teris. Stem 4-8f. high. Hds. on short stalks, Rays 4/ long, entire. W.8 
7 O. grandifio’ra St. 1-2f high. Heads on lung stalks. Bays 1/ long, 4-5-vlefs. 8 
