688 



THE PLANE. 



lie concealed in a hollow into which they fit after the fashion of 

 a finger-tip into a thimble. 



At the fall of the leaf, the bud is exposed, though still amply 

 protected by the scales and stipules which envelop it as if with one 

 or more caps. In spring the expansion of the bud makes the outer- 

 most cap (which is smooth and coloured a reddish brown), split open ; 

 the inner caps then become visible, and enlarge before splitting in 

 their turn. The first to emerge is covered with a gummy substance, 

 the rest are densely coated with brown fur. A similar coating of 

 dull brown fur attracts one's attention to the young leaves when they 

 appear about the middle of May, as well as the unusual way in 

 which they are rolled round from the two outer margins backwards 

 to the central rib, so that the upper surface of the blade alone is 

 partially visible. Still more unusual is the stipular sheath which 

 surrounds the new shoot like a cup with a frilled margin. The 

 under surface of the leaf is hairy, but greener in colour than the 

 upper surface at this early stage. After expansion the young leaves 

 gradually become flat, and loose their woolly coats. The fully- 

 developed leaf usually has three lobes, 

 but leaves on the same tree take very 

 various shapes, the plan of which is 

 best explained by the illustrations. 

 The base oi leaves with an otherwise 

 serrated margin forms an unbroken 

 line. The upper surface of the blade 

 is a very bright rich and shining 

 green : the under-side is duller and 

 tinted with yellow. The whole leaf 

 lies in one plane, with its surface 





