BULLETIN 231] WALNUT CULTURE IN CALIFORNIA. 129 



occurs in river bottoms and stream banks in western California, extend- 

 ing from Los Angeles County northward to Napa County. It is a very 

 beautiful tree, attaining a height of 60 feet, with a trunk diameter of 

 20 inches. Sometimes, however, it is reduced to a shrub." 



Locally it has long been noted that there are in California two more 

 or less distinct species of native walnut, that of the north and that of 

 the south. Some have classed the southern form as Juglans rupestris, 

 but very little observation is necessary to show that the native walnut 

 of southern California is not that which is included under this name. 

 Jepson, 1 in the Bulletin of the Southern California Academy of Sci- 

 ences, discusses this matter, concluding that Watson undoubtedly had 

 in mind the southern California form, and that, therefore, this must 

 be taken as the type of Juglans calif ornica. For the northern form he 

 proposes the name Juglans calif ornica, var. hindsii, naming it in honor 

 of Richard Brinsley Hinds, botanist of the Sulphur Expedition, who 

 first discovered the California walnut on the lower Sacramento River 

 in 1837. In a later work Jepson 2 again classes all the California native 

 walnuts under the species calif ornica, stating that "The northern form, 

 named var. Hindsii Jepson, is characterized by its distinctly arbore- 

 ous form, tall trunks and larger fruits (1J to 2 inches in diameter). 

 Such differences may be readily attributable to the climatic and soil 

 conditions of the northern habitat." 



The study of the native California black walnut having become of 

 considerable importance in this work in connection with the subject 

 of rootstocks for the English walnut, we have given no little attention 

 to an effort to determine the true relationships of the black walnuts 

 found growing in various portions of the State. As Jepson and others 

 have noted, there is a marked segregation of these trees into the north- 

 ern or central and the southern portions of the State, with a broad ter- 

 ritory between, in which it is evident that at the present time at least 

 no native walnuts occur. 



NORTHERN CALIFORNIA BLACK WALNUTS. 



In the upper portion of the State no tree is more conspicuous as a 

 shade and street tree, especially about the older towns, than that which 

 is called the California black walnut. Among these may be found many 

 specimens of the eastern walnut, Juglans nigra, which may be easily 

 identified by their rough nuts, late development in spring and early 

 shedding of the leaves in the fall. Excluding these, there remain 

 very numerous specimens of the so-called true California walnut, a 



'Vol. VII, No. 1, p. 23, 1908. 

 2 The Silva of California. 



2231 



