NOTES ON AMERICAN WILLOWS. IV 



SPECIES AND VARIETIES OF SECTION LONGIFOLIAE 

 Camillo Schneider 



In my paper on Mexican willows (Bot. Gaz. 65:22. 1918) I 

 have already dealt with some species of this well marked and 

 entirely American section. In this article I intend to discuss all the 

 members of this interesting group, which is, as M. S. Bebb (1891) 

 and W. W. Rowlee (1900) rightly stated, clearly defined from the 

 other sections of the genus in both the New and the Old World. 

 Andersson (1858) was the first to recognize the close relationship 

 of species like S. sessilijolia Nutt., S. Hindsiana Benth., and S. 

 taxifolia Kth. to S. longifolia Muhl. Unfortunately he misunder- 

 stood most of the species described by Nuttall, and therefore he 

 did not give, even in 1868, a proper analysis of the forms of this 

 section. In 1900 W. W. Rowlee (Bull. Torr. Bot. Club 27:247) 

 made an attempt to rehabilitate all of Nuttall's species, and 

 described several new species and varieties from the southwest, 

 especially from California. His interpretation of Nuttall's 

 species, however, is not free from grave errors owing to the lack 

 of sufficient t^'pe material. Later C. V. Peper studied those types 

 of Nuttall which are preserved in the British Museum, and com- 

 municated his notes to C. R. Ball, who in 191 5 (Bot. Gaz. 60:49) 

 was able to identify S. sessilifolia and S. fluviatilis Nutt. I have 

 not seen the t>'pes in the British Museum, but I have photographs 

 of Nuttall's specimens of S. exigua, S. macrostachya, and S. 

 melanopsis from the Herbarium of the Academy of Science at 

 Philadelphia. Besides this I have also examined a few of 

 Nuttall's willows at the Gray Herbarium, which also contains 

 some cotypes of forms described by Andersson. Photographs and 

 fragments of Andersson's types from the Hookerian Herbarium 

 at Kew are now in possession of the Arnold Arboretum, and Pro- 

 fessor W. W. Rowlee kindly sent me the types of his new species 

 and forms so far as they are preserved in the Herbarium of Cornell 



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