Carrière states that this tree arose from a cross between J. regia and J. nigra. The leaves are identical with those of J. Vilmoriniana. The young shoots differ in having a glandular pubescence. The fruits are long-stalked and pear-shaped, but otherwise closely resemble those of J. nigra. Young trees of this kind are in cultiva- tion at Kew.
3. Other hybrids between these species have been described. One mentioned by Sargent was an immense tree, found in 1888 by Prof. Rothrock on the Rowe Farm on the north bank of the Lower James River, Virginia. It is described as having the habit, foliage, and general appearance of J. regia, but producing a nut not unlike that of the black walnut, though longer and less deeply sculptured. The nut is exactly like that of Juglans regia gibbosa, Carrière,! which was raised by a nurseryman at Fontenay-aux-Roses in 1848.
De Candolle also described,? as Juglans regia intermedia, a tree which was found at the Trianon, and supposed to be a cross between the common and black walnuts. M.C. de Candolle informed Elwes that a similar hybrid exists at Geneva, and that its seedlings have characters intermediate between the two parents.
There are specimens at Kew, which were sent by Mr. E. Lyon in 1901 from Hurley, Marlow, where there is a fine old tree of Juglans nigra, from the seed of which plants were raised, which are apparently intermediate between that species and the common walnut.
II. Juglans regia x cinerea. Juglans alata, Carrière,’ Rev, Hort. 1865, p. 447. This is described as having young shoots pubescent : leaflets seven to nine, with the end leaflet stalked, the others subsessile ; all oval or elliptic-lanceolate, abruptly acuminate, obscurely and remotely serrate, pubescent on both surfaces: rachis shortly pubescent. Three trees, presumably of this hybrid, have been observed near Boston in the United States; and a description and figure of them are given in Garden and Forest, 1894, p. 435, fig. 69.
III. Juglans regia x californica. A remarkable hybrid between the common walnut and the Californian wild species, has been obtained by Luther Burbank, who names it "paradox.” *
Distribution
The common walnut has a very wide distribution, occurring wild in Europe in Greece, Bosnia, Servia, Herzegovina, Albania, and Bulgaria; and extending eastward through Asia Minor, the Caucasus, Persia, and the Himalayas to Burma and North China and Japan. Its occurrence as an indigenous plant in Greece was first demon- strated by Heldreich,® who found it growing wild in Ætolia at Korax, in Phthiotis on the Œta and Kukkos mountains, and in Eurytania on Veluchi, Chelidoni, etc. It grows wild in Greece in mixture with oaks and chestnuts in great quantity, especially
1 Rev. Hort. 1860, p. 99, figs. 21–23, and 1861, p. 428, figs. 101–103. Rehder considers this hybrid to be the same as J. Vilmoriniana.
2 Ann. Sc. Nat. Sér. iv. xviii. t. 4.
3 This is probably the same as Juglans intermedia guadrangulata, Carrière, Rev. Hort. 1870, p. 493, figs. 66–68.
4 Garden and Forest, 1894, p. 436.
5 Verhand. Bot. Vereins Prov. Brandenburg, 150 (1879).
