296 COMPOSIT^E. Bidens. 



leaves, and solitary or paniculate heads of naostly yellow (sometimes white, rarely 

 purple) flowers ; in summer or autumn. — Linn. Gen. no. 932 ; DC. Prodr. v. 

 593 ; Benth. & Hook. Gen. ii. 387. 



§ 1. PlatycakpJia, DC. Akenes flat, from obovate to cuneiform, not at all 

 contracted at the summit, 2-4-awned : outer involucre foliaceous and spreading : 

 veins of the leaves commonly terminating in the sinuses : ours annuals. 



* Heads erect, rayless, or rarelj' with one to five small rays, these usually shorter than the disk 

 and therefore inconspicuous: disk greenish yellow: leaves mostly petioled. 



B. frondosa, L. (Stick-tight.) Glabrous or somewhat hairy, branching, 2 to 6 feet 

 high : leaves except the uppermost pinnately 3-5-divided into lanceolate or broader sharply 

 serrate and pinuately veiny commonly petiolulate leaflets : outer involucre often very leafy : 

 akenes obovate or oblong, more or less hairy (the hairs of the margin ascending except uear 

 the summit), 2-awned. — Spec. ii. 832; Torr. & Gray, Fl. ii. 351. — Shady or moist ground, 

 preferring manured soil, Florida and Texas to Saskatchewan and Brit. Columbia, every- 

 where common, and with the habit of a naturalized weed. Near Philadelphia, along with 

 this and Coreopsis bidentoides, occurs a form with upwardly hispidulous awns, doubtless a 

 hybrid. 



B. COnnata, Muhl. Glabrous, a footor two high, loosely branched : leaves either all un- 

 divided, oblong or broadly lanceolate, acuminate at both ends, sharply serrate, tapering 

 into margined petioles or the upper sessile ; or some with a pair of lateral divisions which 

 are sessile and decurrent on the petiole : akenes oblong-cuneate or the outermo.st obovate, 

 nearly glabrous but retrorsely hispid-ciliate, commonly 3-awned. — Willd. Sjiec. iii. 1718; 

 DC. i. c. ; Torr. & Gray, 1. c. B. tripartita, Bigel. Fl. Bost. ed. 2, 294, not L. B. petiolata, 

 Nutt. Jour. Acad. Philad. vii. 99, a thin-leaved small-headed form ; while var. coviosa. Gray, 

 Man. 261, is a stout and larger-headed form with ver}^ leafy involucre. Slender forms imi- 

 tate Coreopsis discoidea. — Wet ground, Canada to Illinois, Missouri, and Georgia. 



* * Heads disposed to nod after anthesis, commonly with conspicuous rays: leaves all sessile 

 and undivided; upper pairs somewhat connate round the stem: margins of the cuneate akenes 

 and the rigid awns retrorsel}' aculeolate-hispid. 



B. cernua, L. Stem glabrous or setnlose-hispid, from a span to a yard high : leaves oblong- 

 lanceolate, coarsely and irregularly sharply serrate : heads conspicuously nodding after an- 

 thesis, commonly surpassed by the foliaceous outer involucre : rays ovate or oval, little 

 surpassing the disk or wanting : akenes usually 4-awned. — Spec. ii. 832 (discoid); Willd. 

 Spec. iir. 1716; Sclik. Handb. t. 235; Fl. Dan. t. 841 ; Torr. & Gray, Fl. ii. 352, with var. 

 elata, a large form of the Pacific coast. B. quadriaristata, var. dentata, Nutt. Trans. Am. 

 Phil. Soc. 1. c. 368. Coreopsis Bidens, L. 1. c. 908, radiate form. — Wet ground, from Hud- 

 son's Bay and Saskatchewan to the Pacific coast, and in the Atlantic States south to Virginia 

 and Misscniri ; at some stations seemingly introduced. (Eu., N. Asia.) 



B. chrysanthemoides, Miciix. Glabrous, often decumljent at base, a foot or two high : 

 leaves lanceolate, rather minutely and evenly serrate : heads rather large, little or not at all 

 nodding : outer involucre seldom surpassing the inner, conspicuously surpassed by the oval 

 or broadly ol^long (usually incli-long) rays: akenes 2-4- (more commonly 2-) awned. — Fl. 

 ii. 136 ; Willd. Spec. iii. 1717 ; Torr. & Gray, 1. c. ; Spnigue, Wild Flowers of Amer. 131, 

 t. 30. B. quadriaristata, DC. 1. c. B. heliantholdes, HBK. Nov. Gen. & Spec. iv. 230. Heli- 

 anthus lavis, L. Spec. ii. 906, viz. PI. Gronov. Fl. Virg., ed. 1, 104 (not of ed. 2). Coreopsis 

 Bidens (& C. per/oliata?), Walt. Car. 215. — Wet grounds, Canada to Florida, Arizona, 

 and California. (Mex., S. Am.) 



§ 2. PsilocarpJ:a, DC. (Ceratocephahis, Vaill.) Akenes narrow, linear- 

 tetragonal ; the outer almost always shorter and more truncate at apex than the 

 inner, which generally taper upward, but are not distinctly rostrate : outer in- 

 volucre seldom foliaceous or enlarged. 



* Leaves mainly divided into 3 to 5 ovate merely serrate divisions or leaflets: rays when present 

 white : annuals, at least with us, varying from pilose-pubescent to nearly glabrous : akenes 4 to 5 



