78 



THE OAK. 



When young, the leaves are red, gradually becoming 

 a bright apple-green, and finally in the autumn be- 

 coming russet-brown in color. Young oaks retain their 

 dead leaves till far into the winter, and even old trees 

 usually have some leaves attached till January. The 

 young leaves secrete small quantities of sweet liquid on 



the superior face of 

 the lamina, and are 

 much visited by bees 

 and wasps ; this honey 

 must come through 

 the membrane. As the 

 leaves approach ma- 

 turity the lamina be- 

 comes bright and 

 hard. 



The arrangement of 

 the leaves is expressed 

 by the fraction two 

 fifths, as already de- 

 scribed, each node giv- 

 ing off one leaf at an 

 open angle, the points 

 of insertion being so arranged that a line drawn from the 

 insertion of a given lower leaf, and joining it to the points 

 of insertion of those above, passes twice round the twig 

 before we arrive at the leaf situated vertically above the 

 one started from, and this upper leaf is the sixth above. 

 Although this is the commonest and normal arrange- 



FIG. 21. A portion of the ultimate rami- 

 fications of the vascular bundles, show- 

 ing tracheids only, isolated from the 

 leaf by maceration. 



