14 



Science of Plant Life 



of the blade. They continue down through the petiole or 

 leafstalk into the interior of the stem. At the base of the 

 Apex petiole there is in many leaves 

 a pair of small appendages, the 

 stipules. These are usually un- 

 important structures, but oc- 

 casionally they are large and 

 bladeUke, and supplement the 

 blade, or even take its place, in 

 food manufacture. The primary 

 divisions of the leaf are the blade, 

 the petiole, and the stipules. 



The leaf made up of tissues. 

 The soft green tissue essential 

 to food production is found 

 chiefly in the blade of the leaf. 

 This may be shown by dissect- 

 ing a fleshy leaf like that of the common houseleek or the 

 live-for-ever. Cutting across the blade of such a leaf, wx 



Fig. 7. 



Lateral vein 



Leaf of vinca, showing the 

 parts of the blade. 



Fig. 8. Leaves showing variety of form and venation: A, orange; B, peach; 

 C, bamboo ; D, nasturtium ; E, poplar ; F, lantana ; G, begonia. 



