PLATE XLVI. GRAY BIRCH. 



1. Flowering branch with immature leaves (s) staminate flowers, (p) pistillate flowers, 



2. Branch with mature leaves and fruiting strobiles, x i. 



3. A winged seed, enlarged. 



4. A strobile scale, enlarged. 



5. A winter branch with a partly developed terminal staminate ament, x i. 



6. Section of a winter twig, enlarged. 



