Like the hickory tree, the butternut shares in the childhood reminiscences of those who have lived on farms or in the country where butternuts are a treat to look forward to each fall. The nuts, which mature early, have a rich, tender kernel of mild flavor. Only the disadvantage of their heavy, corrugated shells prevents them from holding the highest place in popularity, although a good variety cracks easily into whole half-kernels.
Butternuts grow over an extended range which makes them the most northern of all our native wild nut trees, although their nuts do not mature as far north as hazelnuts do. Butternut trees blossom so early that in northern latitudes the blossoms are frequently killed in late spring frosts. Only when the trees are growing near the summit of a steep hillside will they be likely to escape such frosts and bear crops regularly. I have found that really heavy crops appear in cycles in natural groves of butternut trees. My observation of them over a period of thirty-two years in their natural habitat in west-central Wisconsin has led me to conclude that one may expect butternut trees to bear, on an average, an enormous crop of nuts once in five years, a fairly large crop once in three years, with little or no crop the remaining years.
As a seedling tree of two or three years, the butternut is indistinguishable from the black walnut except to a very discerning and practiced eye, especially in the autumn after its leaves have fallen. As the trees grow older, the difference in their bark becomes more apparent, that of the butternut remaining smooth for many years, as contrasted to the bark on black walnut trees which begins to roughen on the main trunk early in its life. Bark on a butternut may still be smooth when the tree is ten years old. Forest seedlings of butternut, when one or two years old, are easily transplanted if the soil is congenial to their growth. Although the tree will do well on many types of soil, it prefers one having a limestone base, just as the English walnut does.
A butternut seedling usually requires several more years of growth than a black walnut does before it comes into bearing, although this varies with climate and soil. It is impossible to be exact, but I think I may safely say that it requires at least ten years of growing before a seedling butternut tree will bear any nuts. Of course, exceptions will occasionally occur.
As a butternut tree matures, it spreads out much like an apple or chestnut tree. Of course, it must have enough room to do so, an important factor in raising any nut tree. Enough room and sunlight hasten bearing-age and insure larger crops of finer nuts. Grafting valuable varieties of butternut on black walnut stock will also hasten bearing. I have had such grafts produce nuts the same year the grafting was done and these trees continued to grow rapidly and produce annually. However, they were not easy to graft, the stubborn reluctance of the butternut top to accept transplantation to a foreign stock being well known. This factor will probably always cause grafted butternut trees to be higher in price than black walnut or hickory. The reverse graft, i.e., black walnut on butternut should never be practiced for although successful, the black walnut overgrows the stock and results in an unproductive tree. Specimens 25 or more years old prove this to be a fact.
Butternut trees are good feeders. They respond well to cultivation and lend themselves to being grafted upon, although, from my own experience, I question their usefulness as a root stock. I have found that when I grafted black walnuts, English walnuts or heartnuts on butternut stock, the top or grafted part of the tree became barren except for an occasional handful of nuts, even on very large trees. Since this has occurred throughout the many years of my nut culture work, I think it should be given serious consideration before butternut is used as a root stock for other species of nut trees.
Weschcke Butternut. Smooth shallow convolutions of shell allow kernels to drop out freely. Drawing by Wm. Kuehn.
I had the good luck to discover an easy-cracking variety of butternut in River Falls, Wisconsin, in 1934, which I have propagated commercially and which carries my name. A medium-sized nut, it has the requisite properties for giving it a varietal name, for it cracks mostly along the sutural lines and its internal structure is so shallow that the kernel will fall out if a half-shell is turned upside down. I received one of those surprises which sometimes occur when a tree is asexually propagated when I grafted scions from this butternut on black walnut stock. The resulting nuts were larger than those on the parent tree and their hulls peeled off with almost no effort. Whether these features continue after the trees become older is something I shall observe with interest.
