A Study of Leaves 



49 



much light, however, is injurious. If we bear in mind these 

 two facts, it will help to explain the meaning of the forms and 

 arrangements. 



Leaves also transpire ; but the plant must not lose too 

 much water. To be able to meet all these conditions, it is 

 not surprising that we find such a variety of forms and arrange- 

 ments. 



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



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

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

 that, calling the lowermost leaf No. i, the third and fifth will 

 be directly over it. The distance from one midrib 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 

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