763 



P. laurifolia cont. 



P. undulata, Hurt. 

 P. viminalis, Lodd. 



P. moscoviensis, Schroeder. Origin uncertain. 



P. nigra, L. ; Eng. Bot. ed. 3, 1. 1302. Europe, North Asia. 

 P. fistula, Hort. 

 P. versicolor, Salisb. 

 P. vistulensis, Hort. 



Var. betulaefolia, Wesmael. 

 P. betulifolia, Pursh. 



P. hudsonica, Michx. Hist. Arbr. Am. iii. 293, t. 10, 

 . f. 1. 



Var. Nolestii. 



P. Nolestii, Hort. 



Var. pyramidalis, Spacli. 

 P. dilatata, Soland. 

 P. fastigiata, Pers. 

 P. italica, Moench. 

 P. pannonica, Hort. 

 P. polonica, Hort. 

 P. pyramidalis, Salisb. 



Var. pyramidalis gigantea. 

 P. fastigiata gigantea. 



P. petrowskyana, Schroeder. Garden origin. 



caiiadensis x suaveolens ? 



P. plantierensis, Simon-Louis, (nigra betulifolia x nigra 



fastigiata ?). Garden origin. 

 P. fastigiata plantierensis, Hort. 



P. rasumowskyana, Schroeder. Garden origin, 

 nigra x suaveolens ? 



