The American butternut (Juglans cinerea) is also a valuable lumber tree. The wood has been used for palace-car finishing and other work requiring a high polish, and the large trees are becoming scarce. The nuts are variable in size, thickness of shell, and size and ease of extraction of the meats. The quality of the select varieties is preferred by many to that of the Persian walnut, as it is tender, crisp, oily, and pleasantly flavored. The drawback is that the rough, hard shells do not fit it as well for use in sitting-room or parlor as the nuts that can be crushed by the nut-cracker. As yet we have no named varieties, and we know of no attempt to improve it by the propagation of select varieties found in all localities where it grows naturally. In its native ranges, apparent hybrids are found with the black walnut. In confirmation of this fact Juglans regia and J. cinerea have been crossed in Europe and also in California. Indeed it seems that all species of the walnut family cross naturally as well as by hand pollination. M. Andre of France reports that his opinions as to the limits of species have undergone change since he saw in the nurseries of the Paris museum seedlings of Juglans regia almost identical with the black walnut. Select varieties of the butternut can be budded or grafted on thrifty young seedlings of the same species, as noted in section (284. Walnut Propagation) and probably also on black-walnut stocks.