76 



COLLEGE BOTANY 



tered along the stem with long intemodes ov in a compiact mass 

 with short internodes. However, the arrangem.eait is primarily 

 with reference to the air and sunlight, and is such that in most 

 plants there is relatively little overlapping or shading (Fig. 58). 



Fig. 57. — Leavea developed for catching insects; (o) leaf from pitcher plant, (6) leaves 

 from Venus fly-trap, (c) leaves from the sundew. 



Structure of the Leaf. — The leaf consists of the same tissues 

 as are found in the stem, and they have the same origin. They 

 are arranged so- as to form fibro-vascular hundles, cortex and 

 epidermis. The fihro-vasctdar hundles are a continuation of 

 those found in the stem. They divide and subdivide and form 

 the venation of the leaf. During the process of division the sieve 

 tissues become less and less prominent and are replaced by paren- 



