Chief functions of the leaf: 

 Photosynthesis. 

 Absorption of gases. 

 Absorption of the sun's energy. 

 Transpiration. 



Important functions of the 

 leaf in common with other 

 plant parts: 



Synthesis of proteids. 



Respiration. 



Digestion. 



Absorbed by the roots: 



Oxygen 



Water. 

 Salts of: 



Potassium. 



Calcium. 



Magnesium. 



Iron. 



Nitrogen. 



Sulphur. 



Phosphorus. 



Absorbed by the leaf: 

 Sun's energy. 

 Oxygen for respiration. 

 Carbon dioxide for photosynthesis. 



Given off from the leaf: 

 Oxygen from photosynthesis. 

 Carbon dioxide from respiration. 

 Water by transpiration. 



Given off from the roots : 

 Carbon dioxide. Possibly in some in- 

 stances organic acids and enzymes. 



Fig. 42. 



Longitudinal diagram of the vegetative parts of a plant, with special reference to the 

 absorption and translocation of materials. In this diagram the dotted highway is 

 the water-conducting area (xylem portion of vascular bundle), and the black highway 

 (phloem portion of the vascular bundle) is the area for conduction of the food made 

 in the leaf. The arrows indicate the direction of flow in these highways. 



