• Hollick: Quercus heterophylla in Clove Valley 33 



almost impossible one, especially in view of the adverse interven- 

 ing topographic features. The alternative theory of the former 

 existence of any parent tree in the Clove Valley seemed likewise 

 to be an extremely improbable one, in view of the proved hybrid 

 origin of Q. heterophylla, which would require that at least one 

 mature tree of Q. Phellos L. must also have been growing there 

 in comparatively recent times, and the presence of any such con- 

 spicuous tree or trees could hardly have escaped detection by 

 those who have explored the woods and examined the trees of the 

 region every year during the past forty-seven years. 



Mr. Davis, however, has supplied the testimony which ap- 

 pears to offer a reasonable explanation, if not the actual solution 

 of the problem. He has informed me that on October 27, 1888, 

 he collected acorns from the Tottenville trees and planted a 

 number of them in the Clove Valley. A reasonable assumption^ 

 therefore, seems to be that the tree in question most probably 

 originated from one of these acorns and that the tree is now 

 twenty -nine years old. 



In this connection it is of interest to calculate the theoretical 

 age of the tree from its dimensions and the known rate of growth 

 of other individuals of the same species, and to note how the 

 results arrived at compare with our assumption in regard to its 

 probable origin and age. Certain definite data are, fortunately, 

 at our disposal as a basis for such a calculation. 



On September 30, 191 1, a one-year-old seedling Q. hetero- 

 phylla, about one foot in height,, was collected at the Tottenville 

 locality by Mr. Norman Taylor and planted in the Brooklyn 

 Botanic Garden. On September 17, 1917, I visited the Garden 

 for the special purpose of examining this seven-year-old tree, on 

 which occasion the following facts were noted and calculations 

 made : 



Height of tree 10 feet, circumference of trunk 4.7 inches 

 (= about 1.5 in. diameter), maximum spread of branches 6 feet. 



The indicated rate of vertical growth, ten feet in seven years, 

 would result in a tree a few inches over forty feet in height in 



