60 



PRACTICAL' BOTANY 



covered with Japanese ivy furnish beautiful examples of leaf 

 mosaics on a large scale, and many of our common house plants 

 illustrate the same phenomenon. In any leaf mosaic many 

 of the leaves occupy a very different position from that which 

 they would have if borne on a vertical stem. 



Fic;. 46. Poison ivy, a root climber 

 Reduced 



57. Obtaining better illumination 

 by climbing. While the "stemlesw" 

 plants and low mosaic formers uti- 

 lize light very advantageously b^ 

 the disposition of their leaves, mam 

 plants get an increased light sup- 

 ply by climbing. On account of the 

 great height and dense growth of 

 tropical forests, climbing plants or // 



Tig. 47. Twining stem of liop 

 reach tlieiv greatest 



development in those regions, often running hundreds of feet 

 to emerge at hist into the blazmg sunlight above the tree tops. 



