Transpiration and Water Movement 87 



the effect of closure of the stomata is made evident in the 

 otherwise more or less normal curve of evaporation. 



51. Amount of transpiration. - - According to Haber- 

 landt, a corn plant may transpire during a single growing 

 season 14 kg. of water, a hemp plant 27, and a sunflower 

 66. : That is to say, a sunflower may transpire more than 



FIG. 25. Portions of epidermis stripped from a leaf of Cyclamen : upper 

 epidermis to the left (no stomata), lower epidermis to the right 

 (6 stomata). 



500 grams per day throughout its entire season, which would 

 mean a very much greater amount during a day of maxi- 

 mum loss. Estimated from the transpiration of a small 

 plant, an apple tree of, say, 30 years old might lose 250 

 pounds per day, possibly 36,000 pounds during a growing 

 season. Therefore, one acre of 40 trees would represent a 



The indications are that these figures are far too low for conditions 

 in the United States generally. 



