WiEGAND : Some Species of Bidexs 400 



pubescent on the back ; leaves somewhat more finely and bluntly 



serrate. 



Wisconsin and Missouri to the Saskatchewan. 



/. //. SJiKttc : Dc\'ils Lake, Mo) 



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Nebraska: Webber, 1886; Clements^ no. 2894, 1893. Missouri: 

 Courtney, Bush, no. 29, 1S92. Saskatchewan, Bourgeau, 1857. 

 Bidens froiidosa is common throughout the Middle and West- 

 ern States, but does not seem to appear in New^ F^ngland. In late 

 autumn it forms a very conspicuous part of the vegetation along 

 roadsides and in waste places, especially where the soil is rich and 

 damp, and may be found in flower from Aug. 15 to Sept. 15 or 

 rarely until Oct. i. 



The plants produce ray flowers in considerable abundance in 

 the earlier heads. They are, however, very caducous, and mostly 

 absent altogether in the later heads ; as a result of w^hich a patch 

 bearing rays early in the season may appear entirely rayless at a 

 later period. Very few plants, if any, are entirely destitute of rays. 



Considerable difficulty has been experienced in deciding 

 whether Linnaeus' plant was of this species or the preceding. The 

 original description which is rather longer than usual character- 

 izes the leaves as pinnate and linear, seeds one half narrower than 

 long, peduncles longer than the leaves ; all of which indicate this 

 species rather than B, inelanocarpa, 



Bidcns frondosa is perhaps the most distinct of all the species 

 in structural characters, although not in general appearance, fts 

 two nearest relatives are B. inelanocarpa and B. tripartita^ from 



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the former of which it may be distinguished by the longer pe- 

 duncles, larger number of involucral bracts, the deltoid inner ones, 

 the pale yellow corolla, form of the sterile ovaries of the ray 

 flowers, and the broad, smooth, brown achenes, and from the lat- 

 ter by the pinnate leaves, long peduncles, outer and inner in- 

 volucre, 5 -toothed corolla and broad achenes. 



Bidejis tripartita L. "of the Old World properly belongs here. 

 It is closely related to B, inelanocarpa and somewhat intermediate 

 between that species and B. frondosa. Through it also B. inelano- 



carpa is connected with B. connata, B. coniosa and B. cernita. The 

 typical form has 3-parted leaves and coarsely serrate divisions with 



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the teeth usually rather blunt ; but the variations are very great 



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