22 



BRITISH FLOWERING PLANTS 



colour to leaves. On them depends the life of plants, 

 and ultimately, therefore, of land animals also. 



Every one knows that plants grown in the dark are 

 unable to produce chlorophyll. But though light is 

 necessary for its production, and 

 though the leaves of our plants are, 

 as a rule, arranged so as to secure 

 the greatest amount of light, still it 

 becomes injurious if too intense. 



In our own country leaves are 

 generally arranged so as to secure 

 the maximum of light and air, as, 

 for instance, those of the Beech 

 (Fig. 7), the Spanish Chestnut 

 (Fig. 8), and the Maple (Fig. 9). 

 We have, however, some shade- 

 loving species, and in hotter regions 

 the tendency becomes greater to 

 avoid the too brilliant sunshine. 

 As familiar examples may be men- 

 tioned the leaves of the Black Poplar (Fig. 10) and 

 Eucalyptus, which are vertical, and those of several 



Fig. 7.— Twig of Beech. 



Fig, 8.— Twig of Chestnut 

 (Castanea). 



Fig. 9.— Twig of Norway Maple. 



New Zealand Veronicas, which are placed in four rows, 

 one under the other. The summer shoots sometimes 

 produced on our forest trees are often pale, the bright 



