PLANTS. 63 



away from the central part of the plant to the outer 

 ends of the roots. In the rosette type, most of the 

 water is directed down the central stem. The 

 leaves of a great many plants slope inward and 

 downward, directing the water falling upon them 

 to the central stem and roots. Indian corn and 

 cabbage are good examples of this kind. 



Nature always fits a plant to meet the conditions 

 of its surroundings; so, it must be that some plants 

 need most water for the central roots, and others 

 need it for the outer ones. 



Looking up into almost any tree, one will find 

 few leaves around the central stem and branches, 

 but very many on the outer twigs. The reason for 

 this is the same as in the other cases given the 

 struggle for light and air. If many leaves were to 

 grow within the circle of the outer ones, so much 

 light would be shut out that but little work could 

 be done by them. This mode of leaf position 

 is particularly noticeable in the elm, the leaves 

 of this tree not only being on the outermost 

 twigs, but the greatest number on the topmost 

 branches, giving that tree its decidedly character- 

 istic shape. 



THE NUMBER AND PARTS OF LEAVES. 



Another feature of leaves which might be classed 

 under arrangement is that of numbers. Each plant 

 requires a certain amount of work to be done for 

 its development, and it takes a certain amount 



