170 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



however, give no reason to suppose that they contain any pecan blood. 

 They resemble those of a good type of Royal hybrid walnut, and are 

 very uniform in appearance. It is, therefore, safe to assume that this 

 tree is a hybrid between nigra and calif ornica, but one which has 

 retained more of the characteristics of the latter species, as the foliage 

 of this tree has considerable resemblance to that of the pecan. We 

 have also found one or two other Royal hybrid trees in the State which 

 bear nuts of an oval form, pointed at one or both ends very much like 

 pecans. 



Another peculiar freak is the so-called walnut-oak hybrid, which has 

 been described and discussed by Babcock.* These peculiar trees orig- 

 inated in Orange County among a lot of seedlings of Juglans cali- 

 f 'ornica. Of the original trees there were about twenty among two 

 thousand seedlings. The foliage of these trees is quite different from 

 that of the walnut and resembles very closely that of a small-leaved 

 oak. The fruit is peculiar, being similar externally in appearance to 

 that of Juglans calif ornica, but peculiar in the structure of the nut. 

 The appearance and general characteristics of the tree are sufficiently 

 characteristic to suggest very strongly that it might be a hybrid between 

 the walnut and live oak tree, which grow in very close association in 

 southern California. Efforts by Professor Babcock have thus far failed, 

 however, to produce such a cross by artificial pollination, and he has 

 come to doubt whether this is the true explanation of the origin of 

 this peculiar form. Since the first lot of trees of this kind was noticed 

 a few other similar individuals have appeared among seedlings of 

 Juglans calif ornica. It should have been said that nuts of some of 

 these trees are fertile and produce seedlings, some of which have foliage 

 like the parent, while others appear to have reverted to the walnut type 

 of leaf. 



The native American species of walnut when grown in California 

 certainly present a unique example of freedom in hybridization and 

 variation. It has not been possible in the present work to go into this 

 matter from a technical standpoint, and we have perhaps already given 

 more space to the subject than it deserves in a publication upon wal- 

 nut culture. We desire, however, to record the status of the matter 

 and call the attention of plant breeders and those interested in similar 

 work to a most promising field of investigation. 



*E. B. Babcock, The Plant World, Vol. 13, No. 2, Teratology in Juglans Cali- 

 f ornica Watson. Silva of California Jepson, p. 50, The Walnut Oak Hybrids. 



