44Q 



COMPOSITAE. 



[Vol. in. 



ii. Bidens aristosa (Michx.) Britton. 



Western Tickseed-Sunflower. 



(Fig. 3948.) 



Coreopsis aristosa Michx. Fl. Bor. Am. 2: 140. 1803. 

 C. aristata Muhl. ; Willd. Sp. PI. 3: 2253. 1804. 

 B. aristosa Britton, Bull. Torr. Club, 20: 281. 1893. 



Annual or biennial; stem much branched, 

 i-3 high. Leaves thin, slender-petioled, pu- 

 bescent beneath, the lower ones pinnately 5-7- 

 divided, 3 / -6 / long, the segments lanceolate, 

 serrate, incised or pinnatifid, acuminate, nar- 

 rowed at the base; upper l'eaves less divided, 

 lanceolate, or merely lobed, sessile or short- 

 petioled; heads numerous, slender-peduncled, 

 i / -2 / broad; outer bracts of the hemispheric in- 

 volucre linear or spatulate, usually ciliate, not 

 surpassing the inner; rays 6-9, obtuse; achenes 

 very flat, oblanceolate or obovate, upwardly 

 ciliate and strigose-pubescent; pappus of 2 slen- 

 der upwardly or downwardly barbed awns, 

 nearly as long as the achene, rarely wanting. 

 In swamps and wet prairies, Illinois to Michigan, south to Louisiana and Missouri. Aug.-Oct. 



12. Bidens involucrata (Nutt.) Brit- 



Kr 



ton. 



I,ong-bracted Tickseed-Sunflower. 

 (Fig. 3949-) 



Coreopsis involucrata Nutt. Journ. Phil. Acad. 7: 



74. 1834. 

 Bidens involucrata Britton, Bull. Torr. Club, 20: 



281. 1893. 



Similar to the two preceding species, minutely 

 pubescent, i-3 high, much branched. Seg- 

 ments of the leaves narrower, linear-lanceolate, 

 incised or pinnatifid, long-acuminate; heads 

 numerous, i / -2 / broad, on slender usually hispid 

 peduncles; outer bracts of the hemispheric in- 

 volucre linear-lanceolate, acuminate, densely 

 hispid and ciliate, much exceeding the inner 

 ones; rays orange at the base; achenes flat, 

 ciliate and strigose; pappus of 2 short teeth. 



In swamps, Illinois to Kansas, Arkansas and 

 Texas. July-Sept. 



13. 



In ponds and streams, Quebec to New Jersey, 



Bidens Beckii Torr. Water 

 Marigold. (Fig. 3950.) 



Bidens Beckii Torr.; Spreng. Neue Entdeck. 2r 

 135. 1821. 



Perennial, aquatic; stems simple, or little 

 branched, 2-8 long. Submersed leaves- 

 sessile, i / -2 / long, repeatedly divided into 

 numerous capillary segments; emersed 

 leaves few, sessile, opposite, or sometimes 

 in 3's, lanceolate or oblong, acute, serrate or 

 laciniate, Yz'-^Yz' long; heads solitary or 

 few, short-peduncled, \'-\y> f broad; involu- 

 cre hemispheric, its bracts oval or oblong, 

 obtusish, glabrous, the outer somewhat 

 shorter than the inner; rays 6-10, obovate, 

 or oblong, obtuse, golden yellow; achenes 

 nearly terete, each end truncate; pappus of 

 3-6 slender awns, downwardly barbed above,, 

 smooth below, divergent, 6 // -i2 // long, 

 west to Manitoba and Missouri. Aug.-Sept. 



