24 



PLANT STUDIES 



one. Perhaps the most complete fitting together of leaves 

 is found in certain ivies, where a regular layer of angular 

 interlocking leaves is formed, the leaves fitting together like 



Fig. 18. A plant {Pellionia) with drooping stems, showing how the leaves are all 

 brought to the lighted side and fitted together. 



the pieces of a mosaic. In fact such an arrangement is 

 known as the mosaic arrangement, and involves such an 

 amount of twisting, displacement, elongation of petioles. 



^'^mixi^ 



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