158 



which mature hiter. There is evidently some question as to what 

 extent, if any, the relative development of the two sexes admits 

 of self-pollination and whether the flowers all yield good pollen. 

 This may differ very decidedly for the various species and clonal 

 varieties in cultivation and for the hybrid seedlings that now exist 

 in considerable number. 



But the self-fruitlessness of chestnuts may involve a lack of 

 fertilization. Even when there is ample self-pollination the ferti- 

 lizations necessary for the development of seeds may not take 

 place. This is a type of sterility very common in plants, which 

 limits yields of fruit in clonal varieties unless there is proper 

 cross-pollination. Cross-pollination between certain varieties may 

 also be incompatible and still further limit fruit-setting, as is the 

 case for certain sweet cherries. 



The statements regarding "self-sterility" of chestnuts do not 

 indicate or specify the degrees or grades of sterility present. In 

 an extreme or complete sterility, fruits do not even start to de- 

 velop. The developments of seedless fruits, as seen for the two 

 trees mentioned above, may be only one grade of the sterilities 

 seen among chestnuts. 



It is evident that cross-pollination is needed to insure adequate 

 yields of nuts by many varieties of chestnuts. This can only be 

 provided for by interplanting varieties whose blooming habits co- 

 ordinate sufficiently to insure proper pollination. If this is not 

 accomplished the intei-planting of two varieties may not increase 

 fruitfulness. It will probably take some study, considerable ex- 

 perimentation, and the results of practical experience in orchard 

 plantings to determine the varieties which pair to give most profit- 

 able results for both. 



It is indeed highly desirable that each variety of chestnuts be 

 carefully studied regarding ( i ) the ability of the various flowers 

 to function, (2) the relative maturity of the tw^o kinds of flowers 

 and of the early and late staminate tlf)wers, and (t,) the require- 

 ments for pollination and fertilization necessary for good yields 

 of nuts. This should give some clue as to what varieties will be 

 most satisfactory for interplanting. Then the commercial culture 

 of chestnuts can proceed with greater certainty of adequate yields 

 and of financial success. 



A. B. Stout 



