BULLETIN 231] WALNUT CULTURE IN CALIFORNIA. 155 



times as great as that of the other seedlings. The rapid growth of some 

 of these hybrid trees is truly astonishing. To such a tree which he 

 obtained in Santa Rosa Mr. Burbank gave the name Paradox, and, as 

 we have said, similar types are of common occurrence in almost every 

 lot of black seedling's originating from a tree near which an English 

 walnut stands. 



The cross takes place just as freely in the opposite direction, so that if 

 the nuts from the English walnut tree be planted, hybrids are likewise 

 present among the seedlings from such nuts. In this case, however, it is 

 much more difficult to distinguish the hybrids from the true English 

 seedlings, inasmuch as there is much less difference in their appearance, 

 particularly during the first year. In after years the hybrids begin to 

 outstrip the others in rapidity of growth and differ from them in their 

 general appearance. Such trees are sometimes found in seedling walnut 

 groves, and become very conspicuous by their great size as compared with 

 the other, trees of the grove. 



There is no noticeable difference in appearance between Paradox trees 

 grown from black walnuts and those grown from English walnuts. 

 Such trees are very slow in coming into bearing and in the majority of 

 instances are always very light producers of nuts. Many of the trees 

 bear enormous crops of catkins and pollen and many of them also pro- 

 duce very numerous pistillate blossoms, but for some reason the latter do 

 not seem to pollenize readily and very few nuts result. The nuts vary 

 considerably in different trees, but all that we have ever seen are inter- 

 mediate in form between the black and English walnuts, extremely hard 

 shelled and of no value whatever for eating purposes. There are a few 

 Paradox trees in the State which some years bear quite abundant crops 

 of nuts, but these in every case stand in close proximity to English wal- 

 nut trees, and it is possible that most of their nuts are pollenized by 

 pollen from the other trees. In the majority of instances, even though 

 the hybrid trees stand in the midst of w r alnut groves where they were 

 planted for English walnut trees and bloom at about the same time as the 

 other trees, they set very few nuts. 



The extent to which crossing takes place between the English w r alnut 

 and various black walnut species varies with the nearness of the trees to 

 one another and also, in a general way, with the degree to which the 

 blooming time of the trees coincides. The percentage of hybrids from 

 certain trees, however, varies decidedly in different seasons. Some years 

 the nuts from a certain black walnut tree which stands near English 

 walnuts will give almost all hybrids, while in other years the seedlings 

 from the same tree will be almost all straight blacks. This difference is 

 presumably accounted for by variation in the blooming time of the tree 

 from year to year. Many trees give commonly as high as 40 or 50. per 



