Oct. 15, 1914 



Water Requirement of Plants 



43 



N.\TIVE AND INTRODUCED GRASSES AND OTHER NATIVE PLANTS 



Two native Colorado plants were included in the 191 2 measurements 

 at Akron, Grindelia squarrosa, or "gum weed," and Artemisia frigida^ 

 or "mountain sage" (PI. II, fig. 3). These plants were carried through 

 the winter in the pots, and only two pots of each set were in good condi- 

 tion in the spring. They both behaved as biennials, forming rosettes 

 in 1 911 and flowering profusely in 191 2. The data (Table XXVI) 

 given for the period from May 20 to August 26 include much of the stored 

 dry matter of the rosettes and root systems elaborated during an earlier 

 period, and consequently the water requirement is somewhat too low. 

 In order to check this, the data based on the total period of growth, 

 which includes the growth and water consumption in 191 1, have also 

 been given. This method of computation increases the water require- 

 ment less than 6 per cent. 



Table XXVI. — Water requirement of native plants at Akron, Colo., in igi2 



Although these are typical native plants of the high plains, they re- 

 quired about 20 per cent more water than Kubanka wheat and rank 

 higher in water consumption than any of the cultivated grains except 

 rye and rice. 



Grasses produce so slowly that it is somewhat difficult to make satis- 

 factory measurements of their water requirement. The 1913 experi- 

 ments (Table XXVH) included pure buffalo grass, mixed grama and 



