LEAVES 



73 



the maJting of food materials of all kinds. These carbohydrates, 

 sugars and starches, are made from the water which has been 

 taken up by the roots and transported to the leaves and the 

 carbon dioxide which is taken directly from the air. The energy 

 for this work is the sunlight, which is absorbed by the chJoro- 



FlG. 53. — Pinnately compound leaf. 



Fig. 54. — Palmately compound leaf. 



phyll. The process is known as photosynthesis, which will 

 be described later (page 195). This process may be expressed 

 by the following formula : 



5H2O + 6CO2 = CgHioOg + 6O2 



(Water) (Carbon (Sugar) (Oxygen) 



dioxide) 



It involves the transpiration or giving off of water, the exchange 

 of atmospheric gases and the absorption of sunlight. Therefore, 



