THE WALNUTS HYBRID WALNUTS. 43 



best quality, is removed entire with but a slight tap, as the shell is very smooth and 

 thin. In form and size the nuts vary as much or more than the shagbark hickory, 

 and no doubt can be much improved by selection and cultivation ; and as they can 

 probably be grown wherever any walnut can be, they should be disseminated as soon 

 as possible. The young trees grow rapidly and are not distinguishable in the nursery 

 rows from J, sieboldiana." 



JUGLANS MANDSHURICA. J 



This species, from eastern Asia, as previously noted, bears a close resemblance to 

 our butternut in habit of growth and foliage, and in the form and appearance of its 

 nuts. Trees grown from seed received from Pekin, China, some years ago and planted 

 at Arnold Arboretum are hardy there and have borne fruit for several years. For 

 pomological purposes this seems to be the least promising of the three kinds, owing 

 to the rough, thick shell of its nut. 



HYBRID WALNUTS. ^ 



The use of both the California walnut (Juglans Californica) and the Eastern black 

 walnut (Juglans nigra) as occasional trees in the Persian walnut orchards of Califor- 

 nia, for the purpose of supplying pollen to fertilize the blossoms and insure crops, 

 has led to considerable inquiry as to the possible or probable results to be obtained 

 by crossing one species of Juglans with another. 



The Vilmorin walnut (pi. 7, fig. 8), supposed to have originated near Paris early 

 in the present century, gives evidence of being a hybrid between Juglans regia and 

 Juglans nigra. Felix Gillet, who grew the specimen from which the illustration was 

 prepared, says of it: "I keep it simply as a curiosity. The nut has the shape of a 

 European walnut, but the hard and rugged shell of the Eastern black walnut. I do 

 not see any direct benefit derived from the crossing of the two species, for it cer- 

 tainly does not improve the European walnut and improves the black walnut but very 

 little. I have several grafted trees of the Vilmorin in bearing ; of these, two trees 

 produced several nuts last year that matured, though the trees produced no male cat- 

 kins; the nuts having [probably] been fertilized by the catkins of Chaberte trees close 

 by. The pistillate bloom on the tips of the nutlets of the Vilmorin is pink colored, 

 while that of other walnuts is white. My trees were covered with those nutlets this 

 spring [1891]; though there were no catkins nor staminate flowers on those trees, I 

 expect that many of the nuts will have been fertilized from the catkins of one or 

 more varieties of regia that grow in the neighborhood and which were in bloom at 

 the same time. The foliage of the Vilmorin is of a much lighter green than that of 

 any variety of J. regia, and the edges of the leaves have small teeth, but not so closely 

 set as those of the Eastern black walnuts." 



In 1877 Luther Burbank crossed Juglans regia on pistillate flowers of Juglans 

 Californica. The resultant nuts were planted in 1878, and in ten years the tree from 

 one made the remarkable growth of 12 inches diameter at 2 feet from the ground. 

 It was then accidentally destroyed. Buds that had previously been secured and set 

 on other stocks show the same luxuriant growth of wood and foliage. Trees of these, 

 four years from bud, transplanted to a hard sidewalk, were in 1891 said to be as 

 large as, and taller than, 18-year-old regias on cultivated ground near by. They are 

 as large as Californica trees 10 years of age; the leaves have a very strong, delight- 

 ful fragrance of new apples, unlike any other tree. The bark is light colored, thin, 

 and very smooth. Specimen leaves nearly a yard in length, and a photograph of the 

 budded tree, sent to the Division of Pomology in 1892, indicate t^at the tree is a 

 shapely, symmetrical grower that furnishes abundant shade. Mr. Burbank says : " No 

 other tree that I have seen, except Eucalyptus, will equal this in growth." This tree 

 has not yet fruited. He has some crosses of J. nigra and J. Californica, of which 

 one is 6 years old and exceedingly handsome. 



