THE DICOTYLEDONS 505 
The seeds of the hazelnuts or filberts are prized as food. The | 
bark and oil of the sweet- or black-birch are employed as | 
flavoring agents and antirheumatics. 
OrriciAL Druc Part Usep BoTANICAL HABITAT 
NAME 
(Oleum Betulz) Volatile oil Betula lenta North America 
Methylis Salicylas 
Oleum Betula Empyreu-  Pyroligneous oil Betula alba Eurasia 
maticum Rectificatum 
UNoFFICIAL Druc 
Birch Bark Bark of stem Betula lenta North America 
Fic. 377.—Quercus infectoria—Branch and nutgall. (Sayre.) 
