262 SALICACEAE 



Conn. The southern half of the state, not common. 



N. Y. Highlands of the Hudson, increasing southward. 



N. J. Bergen, Hudson, Middlesex and Cumberland counties, not 



common; also at Cape May Court House. 

 Pa. Chester and Delaware counties. 



Tertiary, o: Cretaceous, not very common: Older Formations, 

 local. 160-204 days. About sea level. 



3. P. candicans Ait. Newf. to N. J. and Va., westward to Mich., 



S. Dak., Alberta and Alaska. In the east mainly an escape 

 from cultivation. 

 A rather uncommon escape in most parts of our range. 



4. P. nigra L. As an escape from cultivation: in the Hudson and 



Delaware valleys. Native of Europe. 



Rare and local in the Delaware Valley. Not recently collected 

 from the lower Hudson Valley; otherwise unknown. 



5. P. deltoides Marsh. In moist soil: Que. to Manitoba, Conn., 



Fla. and Tenn. Rare in our range. 



Conn. In the valley of the Connecticut, Housatonic and Farming- 

 ton rivers; rare elsewhere. 



N. Y. Bronx Co. ; Highlands of the Hudson, increasing northward. 



N. J. Known only from islands in the Delaware River in 

 Warren Co. 

 Tertiary, o: Cretaceous, o: Older Formations, not common. 



Rare or wanting south of the moraine. 161-187 days. Sea level- 



815 ft. 



6. P. grandidentata Michx. In rich soil: N. S. to Del., along 



the mountains to N. Car., west to Ont., Minn., 111. and Tenn. 



Conn. Throughout. 



N. Y. Frequent on L. I., and S. I., increasing and common 



northward. 

 N. J. Throughout the state, increasing and common northward; 



rare and perhaps only adventive in the pine-barrens. 

 Pa. Throughout, more common northward. 



7. P. tremuloides Michx. In sandy, gravelly, or rocky soil: 



Newf. to Alaska, south to N. Y., Pa., Ky., west to Mo. and 

 Neb.; and Lower Calif. 



Throughout the range, except the pine-barrens and south of them, 

 apparently always increasing northward. 



