120 



LEAF-MOSAIC 



[CH. 



But it must not be forgotten that the leaves of suckers 

 and gourmandisers are also usually larger, even in full 

 light ; this seems referable rather to the large stores of 

 reserve materials they have to draw upon. 



In spite of these, and many other difficulties which at 

 present obscure this subject, however, the fact remains 



Fig. 28. Lateral shoot of Ulmus, Elm, showing leaf-mosaic (K). 



that the length of internodes, sizes and shapes of laminae, 

 relative elongation of petioles, and the various movements 

 of leaves, do generally fall in with the achievement of 

 such disposition of the leaves on the spray at the outside 

 of the crown of foliage, that the lamina? are exposed as 

 fully as possible to the incident light and surrounding air. 

 We have only to look at the undisturbed spray of an 

 Elm (Fig. 28), an Ivy on the ground (Fig. 27), or of a 

 Maple, a terraced Cedar or Silver Fir and so on to 

 gather the impression that such is the case, and the 



