334 COMPOSITAE 



4. Coreopsis verticillata L. WhorlEd Tickseed. (Man. p. 999; 

 I. F. /. 393 r.) In dry soil, western Ont. to northern Mich., Md., N. C, 

 Ky., Neb. and Ark, — Pennsylvania : Northampton, escaped. 



5. Coreopsis tripteris L. Tall Tickseed. (Man. p. 999; I. F. /. 

 393/.) In moist woods and thickets, Pa. to Wis., Kans., Va., Fla. and 

 La. — Pennsylvania : Lancaster ; York ; Perry ; Elk ; Westmore- 

 land ; Armstrong ; Lycoming ; Clarion ; Allegheny. 



34. BIDENS L. 



Terrestrial plants : leaf-blades simple, toothed or divided. 

 Leaf-blades serrate or rarely lobed. 



Ray-flowers with conspicuous ligules twice as long as the disk or more. 



I. B. laevis. 

 Ray-flowers with very short ligules, or wanting. 



Heads nodding, at least after anthesis. 2. B. cernua. 



Heads persistently erect. 



Pappus-awns downwardly barbed. 

 Bracts of the involucre not foliaceous : corollas orange : stems 



purple. 3. B. connata. 



Bracts of the involucre foliaceous : corollas greenish yellow : stem 

 straw-colored. 4. B. comosa. 



Pappus-awns upwardly barbed. 5. B. bidentoides. 



Leaf-blades, at least some of them, pinnately 1-3-parted or 1-3-divided. 

 Ligules of the ray-flowers inconspicuous, rudimentary or wanting. 

 Achenes flat. 



Outer bracts of the involucre 4-8 : achenes nearly black. 

 Achenes 4-4.5 mm. long, the awns very short : outer bracts 4. 



6. B. discoidea. 

 Achenes about 6 mm. long, the awns % as long as the body : outer 

 bracts 6-8. 7. B. frondosa. 



Outer bracts of the involucre 10-16 : achenes brown. 



8. B. vulgata. 

 Achenes acerose. 9. B. bipinna/a. 



Ligules of the ray-flowers large and conspicuous. 

 Achenes obovate, very flat. 10. B. involucrata. 



Achenes cuneate or linear-cuneate. n. B. trichospernia. 



Aquatic plant : leaf-blades, at least those of submersed leaves, filiformly dis- 

 sected. 12. B. Beckii. 



1. Bidens laevis (L. ) B.S.P. Larger Bur Marigold. (Man. p. 

 1000 ; I. F. f. 3938. ) In swamps and wet meadows, Mass. to N. C and 

 western N. Y. — Pennsylvania : Bucks ; Delaware. 



2. Bidens cernua L. Sm.a.ller Bur-Marigold. (Man. p. looi ; 

 I. F. /. 3939.) In wet soil, N. S. to Hudson Bay and B. C, south to N. 

 C, Mo. and Calif. Also in Eu. and Asia. — Pennsylvania : Pike ; North- 

 ampton ; Delaware ; Lancaster ; Armstrong. 



3. Bidens connata Muhl. Purple stemmed Swamp Beggar-ticks. ■ 

 (Man. p. looi ; I. F. f. 39-/0.) In swamps or moist soil, N. S. to the N. 

 W. Terr., south to Del., Ga., Ky. and Mo. — Pennsylvania : Northamp- 

 ton ; Bucks ; Delaware ; Chester ; Lancaster ; Franklin. 



