152 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



FOREIGN WALNUT SPECIES. 



There is, as stated in our quotation from Professor Sargent's work 

 on page 171, a considerable number of native walnut species in various 

 parts of the world. Of these, the following are of some importance in 

 California : 



Juglans sieboldiana Maxim. This forms a good sized tree, bearing 

 nuts in long clusters or racemes with sometimes as many as twenty 

 in a cluster. The nuts are very hard shelled, rather long and pointed, 

 with a fairly smooth surface. The best and oldest specimen of this 

 tree in California is one at the Tower House in Shasta County, on the 

 road between Redding and Weaverville. This tree was planted about 

 1860, and is now a large, fine specimen, bearing heavy crops of nuts 

 every year. Another bearing tree may be seen on the grounds of the 

 old Experiment Station near Pomona, and there are probably others 

 in the State. The species is a native of the mountains of northern 

 Japan and is hardy, vigorous and of rapid growth. It is at present 

 of no economic importance in this State. 



Juglans cordiformis Maxim. A Japanese species considerably like the 

 last, trees of which are sometimes offered by nurserymen. There appears 

 to be some doubt whether this is more than a variety of Juglans siebol- 

 diana, differing in the shape of the nut, which is heart-shaped, flattened 

 and pointed at one end, with a shallow groove in the middle of the flat 

 sides. 



Juglans mandshurica. A species sometimes offered by nurserymen, 

 originating in Manchuria. Said by some to be simply a variety of the 

 English walnut. 



Juglans boliviensis. A species supposedly native of Bolivia, which is 

 said to form forests of fine, large, vigorous growing trees in that country. 

 This form has been secured by Mr. Frank A. Leib, of San Jose, from 

 whom we have received scions and produced young trees of this species. 



Pterocarya caucasica. We have obtained scions of this species, which 

 is supposed to be the Caucasian walnut of commerce, from Mr. George 

 Payne, of San Jose, who raised trees from seed. The seed is very small 

 and not at all like that of ordinary walnuts. 



HYBRID WALNUTS. 



The readiness with which different species of Juglans hybridize or 

 cross with one another is quite remarkable. To such an extent does 

 crossing of this sort take place in California wherever two species grow 

 anywhere near each other, that hybrid trees are extremely common in 

 every part of the State under such conditions. In the vicinity of most 

 of the northern towns, like San Jose, Stockton, Santa Rosa, Napa. Vaca- 



