igi6] SHERFF—BIDENS 5°5 



Pittonia 4:254. 1901; Bidcus lugcns Greene, loc. at.; Bidcns formosa 

 Greene, loc. cit. 264; Bidcns Parryi Greene, loc. cit. 265; Bidcns 

 pcrsicae- folia Greene, loc. cit. 266. 



The types of Bidcns chrysanthemoides Michx. and B. hclianthoidcs 

 H.B.K. (both in Herb. Mus. Hist. Nat. Paris) appear precisely the 

 same. The original description of both species shows their achenes 

 to have been 2-aristate in each case, although many specimens have 

 since been gathered showing the achenes often 3 or 4-aristate. A 

 study of numerous specimens from the United States and Mexico 

 seems to indicate a slight tendency for the western specimens to be 

 more often 2-aristate, the eastern ones more often 3 or 4-aristate. 

 But the variations are so abundant as to defy all attempts at 

 delimiting the separate forms or races in a specific way (cf. Torr. 

 and Gr. Fl. N. Amer. 2:353. 1842). 



Greene cites a single sheet for B. formosa, a plant from Dela- 

 ware County, Pennsylvania. But in the Field Museum are 5 

 sheets of material (all by /. A". Small, Wetzel's Swamp, N. Harris- 

 burg, September 1887) from the same state, and these show all 

 gradations between B. formosa and B. lacvis. Again, Greene 

 terms his B. Parryi an unwelcome species, "as uniting the habit 

 of B. cemua and the fruit of the Platycarpaea group of species." 

 But even if B. Parryi were a valid species, it would not be the first 

 species to do this; for all the material of B. lacvis that has flat, 

 biaristate achenes does the same; and, moreover, B. radiata Thuill. 

 (B. plalyccphala Oerst.) had long been noted as a species that 

 likewise united B. cemua with B. tripartita, the latter a principal 

 species of the Platycarpaea group (cf. G. Schweinfurth, Verhand. 

 Bot. Verein Prov. Brand. 2:145. 1861). Indeed, Greene himself, 

 on another occasion (loc. cit. 261) had been led to consider B. radiata 

 in this same connection, having suspected his B. Icptopoda as being 

 this species. DeCandolle, in monographing the genus Bidcns 

 (Prodr. 5:594. 1836), defined the subgeneric section Platycarpaea 

 with the evident purpose of admitting just such species as 

 B. cemua, and actually classed B. cemua among the Platycarpaea. 



Hence Gray saw this plant and determined it personally. As his knowledge of this 

 species was very keen, there is no question as to his accuracy. Linnaeus' private 

 specimen of Hdianlhus laevis L. (in Herb. Linn.) is Hcliopsis (cf. Gray, Synopt. Fl. 

 i":255. 1884; also Persoon, Synops. Plant. 2:473. 1807). 



