l')d 



p. berolinensis, Dippel. Origin uncertain. 

 P, laurifolia var. berolinensis, Hort. 

 P. hybrida rar. berolinensis, C. Koch. 

 P. balsamifera berolinensis, Hurt. 

 P hiurifoiia x deltoidea ? 



P. canescens, >Siii. ; Eng. Bot. ed. 3, 1. 1300. " Gray Poplar." 

 P. albo-tremula, Krausse. 



P. certinensis, Hort. Garden origin. 



P. deltoidea, Marsh. ; Sargent Silva of North America 

 tt. 4'J4, 41).'). North America. " Cottonwood." 



P. Acladesca, LindL 



P. angulata, Ait. 



P. angulosa, Mich.v. 



P. canatlensis, Moench. 



P. carolinensis, Moe7ich. 



P. cordata, Hort. 



P. diJatata rar. carolinensis, Willd. 



P. glandulosa, Moench. 



P. heterophylla, Duroi (^not L.). 



P. laevigata, -4/7. 



P. latit'olia, Mornr/i. 



P. macropliylla, Hort. 



P. marylandica, Bosc. 



P. monilifera. ^/7. 



P. nigra, Marsh, (not 7^.). 



P. nigra ra/-. helvetica, Poir. 



P nigra ra/\ virginiana, Gastii//. 



P. serotina, Hartig. 



P. virginiana, Fouger. . 



