A Study of Leaves 47 



Leaves breathe ; they must have air. They also transpire ; 

 but the plant must not lose too much water. To be able to do 

 all this, it is not surprising that we find such a variety of forms 

 and arrangements. 



The leaves of the Orchid in Fig. 56 have broad bases which 

 encircle the stem. They are arranged in two rows, so that, 

 calline^ the lowermost leaf No. i, the third and fifth will be 



Fig. 56. — Orchid stem with leaves arranged on opposite sides of the stem. 



directly over it. The distance from one mid rib to another is 

 one-half the distance around the stem. 



Canna and Kei apple have broad thin leaves, the fourth is 

 over the first, so that the second and third are exposed to the 

 light. The distance from the midrib of one leaf to that of 

 another is one-third the distance around the stem. What leaf 

 will come over the fourth? You can tell by drawing a spiral 



