1920] SHERFF— TARAXACUM 343 



He stated that "its most constant peculiarity is that of a very 

 dark-colored, almost blackish, involucre, of which the outer scales 

 are very broad, strictly erect, and imbricated." Reference to 

 Ledebour's work, however, shows that this was essentially the 

 form which Ledebour described from Kamchatka as T. cerato- 

 phorum ("squamis omnibus erectis; exterioribus lato-lanceolatis, 

 nigricantibus" etc.), 8 hence T. Chamissonis is to be regarded as 

 typical T. ceratophorum. 



T. lacerum Greene and T. mutilum Greene are plainly mere 

 foliage forms of T. ceratophorum. The type sheet of T. lacerum 

 (in Hb. Can.) bears four small plants. These are not noticeably 

 different from ordinary T. ceratophorum except as to the unique 

 leaves, 9 which consist only "of a linear rachis-like body and a few 

 pairs of divaricate or retrorse subulate-linear or falcate lobes." 

 The bracts are highly ceratophorous. I have not been permitted 

 to examine the type of T. mutilum (in Hb. Mo. Bot. Gard.), but 

 an excellent cotype, previously cited, is in the U.S. National 

 Herbarium. 10 This has leaves slightly less reduced than in T. 

 lacerum, but bracts practically as corniculate. It is matched very 

 closely by /. M. Macoun's plant from Churchill, Hudson Bay 

 (Hb. Can. 79286), and, somewhat less closely, by White and 

 Schuchert no from Baffin Land. The discontinuous distribution 

 indicated by the four collections (T. lacerum from northern bound- 

 ary of British Columbia, T. mutilum from Johnson River in 

 Alaska, from along Hudson Bay, and from Baffin Land), suggests 

 that either these forms represent one valid species of highly 

 interrupted range or else they are merely foliage forms of T. 



8 Fl. Altaica 4:149. 1833. In his still earlier work (Icon. pi. Fl. Ross. 1:9. 

 1829), Ledebour gave only an abridged description: "L. anthodii squamis erectis 

 infra apicem longe corniculatis; exterioribus lato-lanceolatis; interioribus lanceolatis 

 foliis runcinato-sinuatis: laciniis inaequalibus; majoribus subtriangularibus. Hab. 

 in Kamtschatka. 4 Fl. Majo, Junio." His accompanying plate {pi. 34) is some- 

 what crude and shows the outer involucre spreading above the middle and consisting 

 of narrowly lanceolate or even linear bracts. Apparently Ledebour himself had 

 noticed this discrepancy; for in his later description in the Flora Altaica, not only 

 did he retain the character "lato-lanceolatis" for the outer bracts, but he actually 

 inserted the word "omnibus" to qualify "squamis erectis." 



» These resemble very closely those figured by Handel-Mazzetti (Monogr. 

 Taraxacum, pi. 5. fig. 2. 1907) for T. balticum, a species unknown to me. 



10 Indeed, Greene himself had even written "type" upon the label of this speci- 

 men, although in his description he listed Hb. Mo. Bot. Gard. as containing the type. 



