composityE. (composite family.) 189 



1. V. encelioides, Benth. & Ilook. A foot or two high, froelv branch- 

 ing, pale and ciiieicuus or sometimes canescent : leaves mostly alternate, and 

 the upper face green, from ovate or cordate to deltoid-lanceolate, variously 

 serrate or laciniate-cientate, most with winged jjeliolcs, and conimonlv with 

 auriculate-dilatea appendage at base: disk three fourths inch in diameter: 

 rays 12 to 15, an inch long, deeply 3-cleft at summit: akenes obovate, mostlv 

 broadly winged and with short awns. — Xhnenesia encelioides, Cav. Frum 

 S. Colorado and Arizona to Texas. 



42. COREOPSIS, L. TiCKSEED. 



Pedunculate heads terminating the branches : rays mostly showy, vellow, 

 party-colored, or rose-colored. In ours the akene is wingless. 



1. C. tinctoria, Nutt. Glabrous, 2 or 3 feet high: leaves opposite and 

 all 1 to 2-pinnately divided into hniceolate or linear divisions: outer involucre 

 short and close: rays ^ to f inch long, either i/ellow trith crimson-brown base or 

 nearlji all crimson brown : dish-Jlowers dark purple or brown : akenes moderotcl'f 

 incurved : pappus none or an obscure border. — From Colorado and Arizona to 

 the Saskatchewan and Texas. 



2. C. involucrata, Nutt. Somewhat pubescent or glabrous, 1 to 3 feet 

 high : leaves opposite and all pinnately 3 to 7-divided or parted ; the divisions 

 serrate, incised, or again cleft: bracts of the outer involucre 12 io 20, mostly 

 surpassing the inner, slender, hispid on the back and margins : rays sometimes 

 an inch long, golden yellow: disk-Jloicers dull yellow: akenes straight, with 2 

 short acute teeth. — Plains of E. Colorado to Texas and W. Illinois. 



43. BIDENS, Tourn. Bur-Marigold. 



Leaves opposite, simple or compound : heads of mostly yellow flowers soli- 

 tary or paniculate. 



§ L Akenes flat, from obovate to cuneiform, not at all contracted at summit, 2 to 4- 

 awned: outer involucre fol iaceous and spreading. 



* Heads erect, ray less, or rarely with 1 to .5 small rays: disk greenish yellow: leaves 



mostly petioled and divided. 



1. B. frondosa, L. Glabrous or s6mewhat hairy, branching, 2 to 6 feet 

 high : leaves except the uppermost pinnately 3 to S-divided into lanceolate or 

 broader sharply serrate petiolulate leaflets: outer involucre «iften very leafy : 

 akenes ol)Ovate or oblong, more or less hairy, 2-awned. — Shady or moist rich 

 ground, common everywhere. The common " Stick-tight." 



* * Heads commonly with conspicuous rays: leaves all sessile and undivided : 



ufiper pairs somewhat connate I'onnd the stem : margins of the cuncate akenes 

 and the rigid awns retrorsely hispid. 



2. B. cernua, L. Stem glabrous or setulose hispid, from a span to a yard 

 high : leaves oblong-lanceolate, coarsely and irregularly sharply serrate : heads 

 conspicuously nodding after anthesis, commonly surpassed by the foliaceous 

 outer involucre : rays ovate or oval, little surpassing the disk or wanting : akenes 

 usually 4 awned. — Across the continent, especially in the more northern lati- 

 tudes In wet grounds. 



