+Heterosis or hybrid vigor:+ The pistillate flowers of certain nut species, such as the almond, chestnuts, and filberts, must be cross-pollinated with pollen from another variety if satisfactorily crops of well filled nuts are to be produced. These species are self-sterile or self-unfruitful. On the other hand all walnut, pecan, and hickory species are self-fertile and cross-fertile, but may be self-unfruitful because of dichogamy, because they may shed their pollen either before or after the stigmas of the pistillate flowers are receptive to it. In all nut species cross-pollination is generally recommended so as to assure a set of nuts. With cross-pollination a better set of nuts is to be expected than with self-pollination, as well as better filling of the kernels. It has recently been found that when the pistillate flowers of a certain variety are cross-pollinated with a pollen from another definite variety the embryo or nut kernel is larger and better filled. This is a manifestation of hybrid vigor, or heterosis. Heterosis has been found in the chestnut and in the pecan. It likely will be found in other nut species. Some day the principles of selected and controlled parentage underlying hybrid vigor may be utilized in producing superior nuts, as these principals are now so widely used in producing hybrid seed corn.
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President Davidson: That paper was so extremely important that I hesitated very much to stop it, but we are already at the point where we should have adjourned. Now, unfortunately, we have some very important things, I think, yet before us, but if the speakers can give their talks from now on in the form of, shall we say, syntheses of the whole thing and give us the conclusions rather than the details, it will be appreciated by us all. Mr. Wilkinson is going to give us a very important talk on what he has done with the propagation of the Lamb curly walnut. Mr. Wilkinson.
The Grafted Curly Walnut as a Timber Tree
J. FORD WILKINSON, Rockport, Indiana
Our native trees are and have always been one of the most valuable resources of this country, and one of the greatest heritages ever to fall to a nation.
Wood has been used by our people since the landing of the Pilgrims, for almost every comfort and purpose in life, from the making of cradles to caskets.
Wood is still one of the principal materials in building homes and furniture, and is used for railroad ties, for paper, and in so many other ways that we could scarcely get along without wood.
The United States is the native home of many species of trees, of which a number are superior in some certain ways for some special purposes. The hickory has no equal for ax handles. As a building-timber where strength and durability are needed the oak ranks among the first. Other species are equally as important for some other uses.
Not to be overlooked are nut trees. They serve the twofold purpose of producing both food for man and wild life, and valuable timber.