VOLUME LXX NUMBER 5 



Reprinted for private circulation from 

 The Botanical Gazette, Vol. LXX, No. 5, November 1920 



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NEW 

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THE 



Botanical Gazette 



NO J 'EMBER 1920 

 NORTH AMERICAN SPECIES OF TARAXACUM 1 



CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 272 



Earl Edward Sherff 



(with plates xxxi-xxxih) 



For many years our knowledge of the American species of 

 Taraxacum has been in a very imperfect and chaotic state. The 

 perusal of the more prominent manuals and floras issued in the 

 United States during the past few decades shows a surprising 

 confusion of forms and multiplicity of specific names. This con- 

 fusion is easily accounted for by the fact that most of the Taraxacum 

 forms tend strongly to intergrade, so much so that many botanists 

 in the past have despaired of their specific segregation. Thus 

 Torrey and Gray (Fl. N. Amer. 2:494. 1843), after describing 

 Taraxacum dens-leonis ( = T. vulgare), wrote as an introduction to 

 their four additional species: "The following species (the characters 

 of which we copy from chiefly de Candolle, who keeps them dis- 

 tinct), as well as nearly all the genuine Taraxaca, are not improbably 



1 Including the West Indies, but not Greenland. The large number of new 



species recently proposed for Greenland by Dahlstedt have made it inadvisable to 



include the Greenland plants until a more abundant supply of Greenland material 



can be obtained for detailed study. So far, however, I have examined no plants 



from Greenland that were not clearly referable either to those species included in 



this treatment or to Taraxacum nivale Lange, a species close to T. lyratum but differ- 



Jvjing in having the achenes glabrous or nearly so. From a study of Dahlstedt's 



O^ work (Archiv f. Botanik 4 8 :i-4i. 1905; ibid., 5 9 :i-44. 1906) and those of his deter- 



"* minations accessible to me, it appears that his "new species" are mostly synonymous 



with Taraxacum lyratum, T. nivale, and T. ceratophorum. 

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