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. 1 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 



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

 in the United States generally. 



