



f 







1920] SH ERF F— TARAXACUM 



'• 



345 



preference. Yet even here we are confronted with difficulty, 

 since the T. dumetorum type specimens (from Dale Creek, Wyoming, 

 in Hb. Greene) are clearly a mere form or variety of true 7\ cerato- 

 phorum. Indeed, an additional "quite typical" specimen cited by 

 Greene {Williams 434) had once been listed by Rydberg himself 

 (Fl. Montana 484. 1900) as T. cerato phorum. Why he later 

 abandoned the name (vide Rydb., FL Rocky Mts. 1034-1035. 

 191 7) is not clear. As already stated, the American specimens 

 from points south of Alaska (as also many from Alaska itself) 

 tend to have external bracts somewhat different from those of 



1 



Bering Sea (that is, typical) material. These exterior bracts vary 

 from dark to light, from short to long, from ovate to lanceolate, 

 from corniculate or widely dilated-bifid at apex to ecorniculate 

 and acute, from appressed to spreading. 13 Occasionally they are 



apicall} 



as the inner bracts. Sometimes both sets of bracts are 

 dilated, sometimes only the outer or inner set. Viewed 

 in the light of these facts, T. dumetorum is seen to be synonymous 

 with T. ceratophorum. 



Handel-Mazzetti (loc. cit. 73), in dealing with T. cerato- 

 phorum, makes a singular segregation of specimens under the 

 separate binomial T. lapponicum Kihlm. The range given is 

 essentially the same as recognized by him for T. cerato phorum. 

 The chief diagnostic distinction relied upon appears to be the 

 ecorniculate character of the bracts. It is with reluctance that I 

 am compelled to reject his treatment. 14 The species concept and 

 " species sense" of one who, like Handel-Mazzetti, has surveyed 

 the entire genus for all the regions of the world, are naturally and 

 very properly entitled to high respect, but the variations in the 

 corniculate character of the bracts are so great in North American 

 specimens as to render illogical and really impossible any such 

 differentiation (cf. footnote 12). It does not also appear that 

 we even have two parallel series, connected, as stated by 

 Handel-Mazzetti. with each other by numerous intermediate 



15 In one specimen from the type locality of T. ccratophorum (C. Wright, Petro- 

 paulovski, Kamchatka, 1853-1856, Hb. U.S. 424073), the outer bracts are lanceolate 

 and their margins are scarious only to a very slight degree. 



14 At least as to North American plants. As to the status of T. lapponicum 

 Kihlm. in Europe, I have seen too few specimens to judge accurately. 



