TRANSPIRATION 7 BEHAVIOR OF RAIX-FOREST PLANTS. 



85 



In spite of the differences which exist between the maximum relative 

 transpiration rates for the several rain-forest herbaceous plants and for 

 the several species of desert ephemerals, when compared among them- 

 selves, a general review of the readings for all of the widely divergent 

 types examined in the work of Livingston, that of Mrs. Shreve, and 

 in my own discovers a much greater uniformity in the amounts of 

 relative transpiration than might be expected in view of the widely 

 dissimilar anatomical characteristics of the plants and the sharply 

 contrasted climates under which they exist. 



Table 31. Showing comparative values of relative transpiration for plants investigated 

 at Tucson, Arizona, and at Cinchona, Jamaica. 



The total annual evaporation recorded at Cinchona is 32. G c.c. per 

 square centimeter of free water surface; that at Tucson is 345 C.C. 

 per square centimeter. 1 The two rates are in the ratio of 1 to 10.6. 



. T 



The higher rate of evaporation at Tucson means that in the ratio =7 



for that region the values for T must be ten times greater than the 



'Shreve, F. Rainfall as a Determinant of Soil Moisture. Plant World, 17 : 9 -26, 1914. 



