BULLETIN 231] WALNUT CULTURE IN CALIFORNIA. 143 



several years ago planting both southern and northern California wal- 

 nuts side by side in nurseries both in the south and in the north. When 

 so grown the resulting trees have shown very marked and constant differ- 

 ences from one another and the characteristics of each type as shown in 

 the nursery have remained constant both in the south and in the north. 

 Seedlings of the southern type are much more branching and bushy than 

 those of the northern, sending out large, lateral branches and secondary 

 stems close to the ground, while the northern seedlings grow erect with 

 one stem and few large laterals. In this way the southern seedlings are 

 broad, bushy and covered with foliage clear to the ground, in marked 

 contrast to the other type. The leaves of the southern tree are some- 

 what smaller, more finely divided and with more sharply pointed leaflets 

 than those of the northern. They are also a little lighter in color and 

 the bark is of a brighter green. One of the most pronounced differences 

 lies in the fact that the southern seedlings come out much earlier in the 

 spring and continue to hold their foliage and grow much later in the fall 

 than the northern, whether they are planted in the south or in the north. 

 This is a most decided difference and holds true constantly, the rows of 

 southern seedlings being always in full leaf in the spring while the 

 northern are still bare, and showing the same condition in the fall for 

 several weeks after the northern California seedlings have dropped all 

 their leaves. This characteristic is one upon which environment, in the 

 first generation at least, has no apparent effect. In the germination of 

 the nuts the two forms also show a difference. Nuts of the southern 

 California type are much quicker to germinate in the spring and when 

 planted in the same conditions invariably sprout much earlier than the 

 northern nuts, whether they be planted in the north or south. 



Another decided difference lies in the relative effect upon trees of the 

 two forms of various conditions such as dryness, heat, etc. An appar- 

 ently physiological disease, which we will discuss later, called the "yel- 

 lows" or "frizzles," affects the northern California type very badly in 

 some instances, but we have never known a southern California seedling 

 to show this disease, even though grown in rows adjoining badly-affected 

 northern California trees. Another disease, nursery root rot, see page 

 379, invariably picks out the southern California black seedlings, never 

 affecting those of the northern type in the same nursery. 



We know of no trees of the southern California type of any consid- 

 erable age now growing in the north. There are several of these trees 

 about four years of age planted by Professor E. B. Babcock on the Uni- 

 versity grounds west of the new agricultural building, and these trees are 

 of the characteristic bushy-topped form, coming out early in the spring 

 and holding their foliage very late in the fall, in marked contrast to 

 trees of the northern type. We have planted southern nuts in several 

 nurseries in the northern part of the State and found that the resulting 



