272 BETULACEAE 



N. J. Rare and local in Mercer, Union, Hunterdon and Somerset 

 counties; increasing but not very common northward. 



Pa. Probably throughout, but not definitely known from Dela- 

 ware or Luzerne counties. 

 Tertiary, o: Cretaceous, o, or perhaps in Bucks Co., Pa.: Older 



Formations, increasing northward. 1 17-189 days. Sea level- 



1,800 ft. 



Corylus heterophylla Fisch. has been recorded from Conn, as an escape. 



4. Betula [Tourn.] L. 



Shrub. I. B. pumila. 



Trees. 



Catkins slender stalked. 



Bark chalky white (sometimes darker in B. papyrifera). 



Leaves deltoid or rhombic. 2. B. populifolia. 



Leaves ovate. 3. B. papyrifera. 



Bark brown or red-brown or green-brown, not white. 4. B. nigra. 



Catkins sessile or very nearly so. 



Fruiting scales glabrous. 5. B. lenta. 



Fruiting scales ciliate. 



Scales 4-5 mm. long, the lateral wings almost basal; 



leaves cordate. 6. B. alleghaniensis. 



Scales 8-10 mm. long, the lateral wings arising in the 



upper half of the scale, leaves rarely cordate. 7. B. lutea. 



1. B. pumila L. In bogs or wet ground: Newf. to Ont. and the 



N. W. Terr., south to N. J., Ohio and Minn. 

 Conn. Northwestern Litchfield Co. 



N. Y. Pine Plains, Dutchess Co., increasing northward. 

 N. J. Morris, Warren and Sussex Co. 



Tertiary, o: Cretaceous, 0: Older Formations, increasing north- 

 ward. Not south of the moraine. 11 7-1 53 days. 650-1,800 ft. 



2. B. populifolia Marsh. Along streams or on hillsides: Prince 



Edward's Is. to Delaware, west to W. N. Y. and E. Pa. 

 Throughout the range except in southern Pa. 



3. B. papyrifera Marsh. In forests: Newf. to Alask., south to 



N. J., Pa., Mich., Neb., Colorado and Wash. 



Conn. Rare and local in the coastal counties, increasing north- 

 westward. 



N. Y. Dutchess Co., increasing but not very common northward. 



N. J. Known only from two isolated stations in Union Co., both 

 perhaps derivatives of cultivation. 



