763 



P. laurifolia — <ont. 



P. undulata, Hu)t. 

 P. viiuinalis, Lodd. 



P. raoscoviensis, Sckroeih-r. Origin uucertaiu. 



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

 P. tistula, Hort. 

 P. versicolor, Salish. 

 P. vistulensis, Hort. 



Var. betulaefolia, WesmwL 



P. betulifolia, Purs/i. 



P. hudsonica, Mirhx. Hist. Arbr. Am. iii. 293. t. ll)» 

 f. 1. 



Var. Nolestii. 



P. Nolestii, Hurl. 



Var. pyramidalis, Spadi. 

 P. dilatata, Soland. ». 

 P. fastigiata. Pers. 

 P. italica, Afoenc/i. 

 P. pannoiiica, Hort. 

 P. poloniea, Hort. 

 P. pyramidalis, S'fitisb. 



Var. pyramidalis gigantea. 

 P. tastitriuta ^iarantea. 



P. petrowskyana. Schrofder. Garden origin, 

 canadensis x suaveolens ? 



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

 fastigiata ?). Garden origin. 



P. fastigiata plantit>ronsis, Hurt. 



P. rasumowskyana, Si^hroedm'. Garden origin, 

 nierra x stiavi'olens ? 



