EMORY OAK IN SOUTHERN ARIZONA. 



lated patches will enable some trees to put on their leaves in a dry 

 season during late April or early May, while most of the trees are leaf- 

 less until June or July. This may result in a broad ring on the favored 

 tiws, while the rest of the stand can make only a narrow one. 



A peculiar growth characterized thousands of acres in the Canelo 

 Hills, where an inch of rain in early June was not followed by any 

 precipitation for a month. Emory oak and Arizona white oak devel- 

 oped leaves, which were not more than from 1 to 2 cm. (0.4 to 0.8 

 inch) long. When the unusual rainy season started in July the June 

 leaves failed to develop further, which indicated that the meristem 

 tissue had lost its function, though the leaves seemed normal in all 

 other respects. New leaves of normal size were formed, and these, 

 at the end of the growing season, were from 10 to 20 times as large as 

 the leaves formed in June. Still another indication of the adapta- 

 bility of the species to changes in growth conditions is the appearance 

 of new leaves and shoots as late as the first of September. 



Sprouts in the valley stands were measured for height and diameter 

 growth, and the results of these measurements are given in Table 1. 

 "Injury sprouts" are those which are the results of accidental 

 harm, such as would come through grazing or fire. The stump 

 sprouts are, of course, those which spring from the stump of a felled 

 tree. 



TABLE 1. Height and diameter growth of sprouts in valley stands. 



1 No stumps were older than 35 years. 



