260 



BIRCH 



about f the length of the midrib ; the lowest much shorter 

 than those in the middle of the leaf, and more divergent, 

 and they are almost devoid of conspicuous outer nerves. 

 Meshes rather loose, not prominent. 



/~7 [~1 Leaf triangular- or rhomboid-cordate or 

 broad-ovate, acuminate; secondaries 5 6 

 pairs, the lower the longest. 



Betula alba, L. Birch (Fig. 94). Small tree, with 

 white periderm, and slender more or less drooping shoots, 



Fig. 94. Birch, Betula alba, p. 260 (Ett). 



bearing thin foliage. Leaf variable, 4 6 x 2 5 cm. 

 (3 9 cm.), broadly deltoid- or rhomboid-cordate to ovate- 

 triangular, or more or less broad-ovate to broadly cuneate; 

 with plane or angular-rounded, or rarely truncate or 



