1914] Baicock: New Variety of Juglans 49 



be remembered that they are the progeny of only two different 

 trees and, if they are the result of asexual reproduction, it would 

 be reasonable to expect among the offspring of either parent 

 marked uniformity in size, leaf characters, time of putting forth 

 and shedding leaves, time of flowering and flower characters. 

 But the variations in the above mentioned characteristics are 

 so great as to suggest heterogeneous i:)arentage within the species 

 rather than asexual reproduction from one or two parent trees. 

 Plate 13, figure 1, and plate 14, figure 2, show a typical leaf and 

 a cluster of partly developed fruits from each of six of these 

 F^ seedlings. 



With these facts in mind, let us consider briefly the various 

 processes of abnormal embryogeny that may have given rise to 

 these variable seedlings. (1) The new sporophyte may have 

 developed from the megaspore mother-cell, in which case its 

 cells would possess the diploid number of chromosomes charac- 

 teristic of Juglans calif ornica, provided that the parent tree was 

 typical of the species. (2) It may have arisen from the mega- 

 spore, from the egg nucleus, or from one of the other embryo 

 sac nuclei, without fertilization, in which case its cells would 

 contain the haploid number of chromosomes. (3) It may have 

 arisen adventitiously from sporophytic tissue, in which case its 

 cells would contain the diploid number of chromosomes. It is 

 obvious that in either the first or third instances we should ex- 

 pect much uniformity among the progeny and close resemblance 

 to the parent trees. Hence, in view of the wide variation men- 

 tioned above, it is reasonable to assume the occurrence of one 

 or more of the three phases of parthenogenesis included in the 

 second of the three cases above defined. 



Finally, this hypothesis of origin by hybridization with oak 

 is practically annihilated by the discovery previously reported 

 that in a row of twenty-one California Black Walnuts, growing 

 in Garden Grove, Orange County, California, a single tree has 

 been found which produces the new variety j^ear after year. I 

 know of no oaks in this region, but even if oaks were abundant 

 and close at hand, the fact that quercina seedlings come from 

 only one tree would certainly indicate some other cause than 

 oak pollination. 



