1913] Babcock: New Form of Juglans 3 



soil conditions. But their structural characteristics alone are 

 sufficient to excite the interest of the student of plants, especially 

 of one interested in problems of heredity and evolution. 



Perhaps the most interesting thing about these trees is their 

 resemblance to oak trees. In mass effect they resemble small- 

 leaved oaks more than walnuts. This is mostly due to the small 

 size of the leaves and to their color, which is a darker or duller 

 shade of green than that of California black walnut leaves. These 

 features, associated with the fact, noted by Disher, that the parent 

 tree stood close beside a coast live oak tree {Quercus agrifolia 

 Nee), are sufficient to account for the view, held by a number of 

 persons, that this new form originated through hybridization 

 between walnut and oak. 



As the seeds were planted in 1901, these trees are now 

 twelve years old. The two retained by Mr. Disher were 

 left in the nursery, which was set out to commercial varieties 

 of walnut {Juglans regia) later on by the owner of the farm. 

 He has allowed the trees to stand unmolested, except for trim- 

 ming up low-hanging branches. Now they have attained a height 

 of twenty-five feet and have a spread of branches about twenty 

 feet in diameter. Seen among the broad-leaved English walnuts, 

 these two trees present a distinct appearance with their many 

 slender branchlets and their sparse foliage. In early spring and 

 late autumn or early winter the contrast is even greater, because 

 these trees and other specimens of the new form resemble south- 

 ern California black walnuts in the brevity of their dormant 

 period. They leaf out very early in spring and some leaves per- 

 sist until February. The English walnuts, however, come into 

 leaf from April to June, according to the variety, and by Nov- 

 ember are once more leafless. 



Other distinctive vegetative characters are well shown in plate 

 1, figure 1. There is a marked tendency to dichotomous branch- 

 ing. This is conspicuous in the left-hand tree in the picture and 

 is noticeable in the other individual. There is also a tendency to 

 form bunches of leaves at the ends of the branchlets. This is 

 apparent in both trees. The appearance of the bark on the 

 trunks of Disher 's original trees is also distinct from that of 

 Juglans californica. AVhile that of the latter in trees of the 



