WORK OF THE LEAVES: TRANSPIRATION 103 



and in an entire leaf of the sunflower there are about 13,000,000 

 stomates. 



164. Amount of water transpired by plants. The amount 

 of water transpired by plants is very great. According to careful 

 estimates, a sunflower 6 feet high transpires on the average about 

 one quart per day; an acre of cabbages 2,000,000 quarts in four 

 months; an oak tree with 700,000 leaves transpires about 180 

 gallons of water per day. According to von Hohnel, a beech tree 

 no years old transpired about 2250 gallons of Water in one sum- 

 mer. A hectare of such trees (about 400 on 2^ acres) would 

 at the same rate transpire about 900,000 gallons, or about 30,000 

 barrels in one summer. 



