Babcock: A New Walnut 



43 



California Black Walnut trees from 

 which Mr. Tyler obtained nvits for his 

 nursery. In 1912 I had the crop from 

 each of 21 of those trees gathered sep- 

 arately and thus selected the particular 

 tree which produces quercina seedlings. 

 This tree is known as No. 16. In 1913 

 I had about 350 clusters of nuts on this 

 tree gathered separately and tested and 

 found that 42 clusters produced the new 

 fonii, but, strange to say, there was 

 only one quercina seedling among those 

 from each cluster, the others being 

 typical black walnuts. A fuller report 

 on this work together with critical dis- 

 cussion appears elsewhere.^ 



NO MENDELISM FOUND. 



No oaks, either native or exotic, are 

 known to occur in the region of Garden 



istics of the mutant and the parent 

 and so reproduces both types. The 

 proportion of californica and quercina 

 seedlings found in the progeny of fruit- 

 ing specimens of the new form is quite 

 different for different specimens. I have 

 tested the seeds from three different 

 quercina trees and can state positively 

 that I have never found any oaks among 

 the progeny nor any Mendelian ratios 

 between the numbers of californica and 

 quercina seedlings produced. These 

 facts considered together with the com- 

 plete absence of specific oak characters 

 in the new form should effectually dis- 

 pel the notion that hybridization with 

 oak has had anything to do with the 

 origin of the new form. 



The original source of the new 

 variet\^ was the tree discovered b\- 



■'■V'- 



NUTS OF PARENT AND MUTANT 



At the left, three nuts of the Southern California black walnut; on the right three nuts of the 

 variety quercina which suddenly appeared as a mutant from it. There is no real distinction 

 between the two nuts, and not the slightest trace, in those on the right, of any influence 

 of an oak, which is alleged by some horticulturists to have been one of the parents of the 

 new form. (Fig. 18.) 



Grove — certainly none in the imme- 

 diate vicinity of tree No. 16. This 

 eliminates the possibility of origin of 

 the quercina progeny of tree No. 16 

 through hybridization with oak. The 

 limitation of the production of quercina 

 seedlings to only one of the 21 black 

 walnut trees tested, indicates that the 

 mutation does not occur in the staminate 

 flowers of No. 16 or its neighbors but 

 rather in the pistillate flowers of No. 16 

 itself. And, further, the fact, which has 

 been amply demonstrated, that the new 

 form does not breed true but usually 

 produces some typical californica seed- 

 lings among its progeny, shows con- 

 clusively that the mutations occur in 

 the pistillate flowers before fertilization, 

 so that each quercina seedling produced 

 by a black walnut tree is a hybrid in the 

 sense that it combines the character- 



Disher in Santa Ana canyon, the parent 

 of the original quercina trees shown in 

 fig. 19. This tree was destroyed before 

 the writer had seen its progeny. The 

 next source to be discovered was a 

 single tree in Santa Monica canyon near 

 Los Angeles. Among a lot of nuts 

 gathered in 1909 from wild walnut trees 

 growing in that region, there was one 

 nut that produced a quercina seedling. 

 The third tree found to produce the new 

 form is No. 16 in Garden Grove, Cali- 

 fornia. The row of trees, of which it is 

 one, was planted perhaps thirty years 

 ago and I have not learned the location 

 of their parents but all the individuals 

 in the row are southern California 

 Black Walnuts. 



The fourth source of the new variety 

 has just been discovered. It is of 

 unusual importance for reasons of 



*Babcock, E. B. Studies in Juglans II. Further Notes and Observations on a New Form of 

 Juglans californica Wats. Univ. of Cal. Pub. Agric. Sciences, vol. 2, No. 2, 1914. 



