BicKNELL : Ferns and flowering plants of Nantucket 15 



planted generations ago, maintain a solitary existence still. 

 Younger trees of most of the species testify to some slight progress 

 in natural increase but, except in the case of Salix Smithiana^ none 

 of the European species can be regarded as really naturalized. 



What appears to be typical Salix fragilis occurs at a few 

 places, but it is not common and seems to be only casually spon- 

 taneous. 



* Salix alba x fragilis Wimmer. 



Less uncommon than typical Salix fi'agilis 2X\6. less doubtfully 

 spontaneous, occurring at widely separated localities sometimes in 

 out of the way places. The trees from different stations show con- 

 siderable variation m the s\z^ and form of the leaves and the pubes-' 

 cence of the younger parts, some individuals evidencing more of 

 their alba parentage, others more that oi fragilis. No unequivo- 

 cal examples of the hybrids Salix decipiens Hofif. and Salix Riissel- 

 liana Smith were found. As a matter of local interest, the willows 

 of this group should be studied in their flowering and fruiting sea- 

 sons and receive careful determination, 



* Salix alba L. 



4 



Infrequent ; typical Salix alba was collected at the border of a 

 swampy thicket in Polpis. Salix vitdlina L. was not observed. 



* Salix babylonica L. 



In a swampy lot on the south side of the town, in a situation 

 where it would scarcely have been planted, a tree of medium size 

 grew in 1899 and 1904 but had disappeared in 1906. This tree 

 was perhaps the parent of two young trees, one about five feet 

 high, observed in 1907 in low fields not far distant. A tree near 

 the cockspur-thorn lot to the west of the town, growing with other 

 introduced trees, was doubtless planted, as well as another tree near 

 it, apparently a hybrid with S. fragilis. 



* Salix Smithiana Willd. 



Salix cinerea x viminalis Wimmer. 



This strongly characterized willow seems to be better adapted 

 to the Nantucket environment than any other of the introduced 

 species, and more than any other may be considered as definitely 

 established. It is frequent in the general town region as well 



