PLANT PHYSIOLOGY AS KELATED TO PRUNING 



23 



or storage is occurring. It remains only to be mentioned 

 that each rootlet and each leaf are more or less directly 

 connected by vascular bundles in more or less definite 

 number, depending upon the species. In leaves these 

 bundles constitute the "ribs" or veins which serve both 

 as conduits and as stiffcners of tlje leaves themselves. 



28. Chlorophyll, the green coloring matter of plants, 

 is the most intimate link which bindslifetothesun. Itisthe 

 laboratory in which is made the^&arth's supply of organic 

 matter, including all fuel. THough sometimes obscured 



Fatisade ^arench 



FIG. 17 DIAGRAM OF CUT EDGE OF LEAF 

 Note the various tissues. (After Stevens, Plant Anatomy.) 



by other colors, it is characteristic of all higher plants, 

 algae and mosses, but is; absent in fungi. Plants contain- 

 ing it may grow in partial shade or in the full glare of the 

 sun, but never in total darkness. The relation of light to 

 chlorophyll is clearly indicated by the sizes and forms 

 of the leaf blades, the arrangement of leaves upon their 



