84 JOURNAL OF THE ARNOLD ARBORETUM [vol. hi 



S. pameachiana Barratt, Salic. Am. no. 16 (1840). See S. alba-Pa- 

 meachiana. 



S. Peasei Fernald. See S. herbacea X Uva-ursi. 



S. petiolaris x S. sericea. Andersson's var. subsericea of S. petiolaris 

 is now commonly regarded as representing this hybrid. In accepting 

 this view I give the following synonymy already published by Topffer. 

 Some authors, however, still regard S. subsericea s. str. as a distinct spe- 

 cies, and are able to distinguish hybrids between it and S. petiolaris, 

 mentioned by Knowlton and Deane in Rhodora, xvi. 108 (1913). — S. 

 neo-Forbesii Topfer in Oestr. Bot. Ztschr. xlvi. 402 (1916). — S. petiolaris 

 2. subsericea Andersson in Svensk. Vet.-Akad. Handl. vi. 109 (1867); in 

 De Candolle, Prodr. xvi 2 , 284 (1868). — S. sericea var. subsericea Rydberg 

 in Britton, Man. 318 (1901). — S. subsericea Schneider, 111. Handl). Laub- 

 holzk. I. 65 (1904), non Doll, (1859); Forbes in Rhodora xi. 9 (1909). 



S. petiolaris x S. tristis. Observed by Forbes and mentioned by 

 Knowlton and Deane in Rhodora, xvi. 109 (1914). 



? S. planifolia var. monica X S. subcoerulea. This cross may be repre- 

 sented by P. A. Rydberg's No. 6812 from Utah, Saltlake County, Big 

 Cottonwood Canyon, below Silverlake, July 8, 1905 (fr. submat.; N.). 



S. rubella Bcbb. See S. Candida X cordata. 



S. subsericea Schneider. See S. petiolaris X sericea. 



Berlin-Daiilem, June, 1921. 



c. SOME REMARKS OX THE GEOGRAPHICAL DISTRIBUTION 



OF THE AMERICAN WILLOWS 1 



Before I conclude my notes on American Willows I wish to say a few 

 words in regard to the geographical distribution of the different sections 

 and species. I suppose it will be of some use to students of the genus and 

 of the flora of a certain state or region in general to give an enumeration 

 of all the species according to their occurrence in the different states 

 based on the material I have been able to examine. Of some states I 

 have seen very little material, and, therefore, my indications are far from 

 exhaustive. I wish to draw the attention of students to the flora of those 

 states or regions where I can give but an incomplete account of the Wil- 

 lows which may occur in them. 



Among the twenty-three sections enumerated by me in another note 

 there are several groups peculiar to America and not represented in the 

 Old World; namely, Sect. Nigrae, Bonplandianae and Longifoliae. Of 

 the Nigrae the typical S. Humboldtiana is restricted to South America, 

 probably ranging as far south as the Straits of Magellan, while its nor- 

 thern representative, S. nigra, reaches the 50th degree N. Lat. in Ontario. 

 No other section covers such a wide area, as it is also found from the 

 Atlantic to the Pacific coast. 



1 Reprinted from Vol. n. 197-204 of this Journal with the addition of the new species 

 and new varieties published since by C. N. Ball, except S. caudaia var. parvifolia which 

 is included under S. lasiaudra var. caudata. 



