COMPOSITAE 



627 



2. C. tinctoria Nutt. In moist soil: Minn, to the N. W. Terr., 



south to Neb., La. and Ariz. Escaped from gardens 



eastward. 



A rare and doubtfully persistent escape from gardens, often 

 locally wanting. 



3. C. verticillata L. In dry soil: western Ont. to northern Mich., 



Md., N. Car., Ky., Neb. and Ark. 



Known in our area only as a rare escape from gardens, doubtfully 

 persistent. 



4. C. lanceolata L. In dry or moist soil: western Ont. to Va., 



Fla., La. and Mo. 



A rare and scarcely persistent escape from gardens, perhaps 

 nowhere established in our range. 



36. Bidens L. 



Plants terrestrial, often of swampy places, erect; leaves simple or 

 divided. 

 Leaves lanceolate, serrate, undivided, rarely Iobed. 

 Rays present, large and conspicuous. 

 Rays sometimes wanting, if present, mostly small. 

 Heads nodding after flowering. 

 Heads persistently erect. 



Pappus awns downwardly barbed. 



Involucral bracts not foliaceous; stem 



usually purple. 

 Involucral bracts foliaceous; stem straw 

 colored. 

 Pappus awns upwardly barbed. 

 Leaves, some or all of them, pinnately 1-3-parted or dissected. 

 Rayi rudimentary, none, or very short. 



Achenes flat ; leaves, some or all of them, 1-3-divided. 

 Outer involucral bracts 4-8; achenes nearly 

 black. 

 Achenes 4-4.5 mm. long; awns very short; 



outer bracts 4. 

 Achenes 6 mm. long; awns half as long as 

 the achene; outer bracts 6-8. 

 Outer involucral bracts 10-16; achenes brown. 

 Achenes linear; leaves dissected. 

 Rays large and conspicuous. 



Achenes cuneate or linear-cuneatc. 

 Achenes obovate, very flat. 



Bracts of the involucre glabrous or ciliate. 

 Bracts of the involucre densely hispid. 

 Plant aquatic; submerged leaves finely dissected. 



1. B. lacvis. 



2. B. cernua. 



3. B. connata. 



4. B. comosa. 



5. B. bidentoides. 



6. B. discoidea. 



7. B. frondosa. 



8. B. vulgata. 



9. B. hipinnata. 



10. B. trickosperma. 



11. B. ariUosa. 



12. B. involucrata. 



13. B. Beckii. 



