46 



TLANTS AND SUNLIGHT 



in Fig. 75. If the pupil were to examine the leaves on the 

 Norway maple, which is photographed in Fig. 75, he would 

 find that leaves which are not on the outside lengthen 

 their leaf -stalks in order to get the light. See Fig. 144. 

 Norway maple is common on lawns and roadsides. 



108. We have seen (84) that a large part of the 

 leaves of any one year are packed away in the buds of 



the previous winter. 

 It is almost impossi- 

 ble that these leaves 

 should be packed 

 away hit or miss. 

 They are usually ar- 

 ranged in a mathe- 

 matical order. We 

 can see this order 

 when the shoot has 

 grown. We can see 

 it by studying the 

 buds on recent shoots, 

 since there was a leaf 

 for each bud. The 

 leaves (or buds) may 

 be opposite each other 

 on the stem, or alter- 

 nate. Fig. 81. 



109. When leaves 

 are opposite, the pairs 

 usually alternate. 

 That is, if one pair stands north and south, the next 

 pair stands east and west. See the box-elder shoot, on 

 the left in Fig. 81. One pair does not shade the pair 

 beneath. The leaves are in four vertical ranks. 



110. There are several kinds of alternate arrangement. 

 In the elm shoot in Fig. 81, the third bud is verti- 



74. A climbing fig choking a palm. 



