Juglans

Plant Characteristics

Habit		tree

Cultivation

Scientific Names

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Read about Juglans in the Standard Cyclopedia of Horticulture

Juglans (ancient Latin name from Jovis glans, nut of Jupiter). Juglandaceae. Walnut. Butternut. Plate LX. Woody plants grown for their handsome foliage and some species for their edible nuts. Deciduous trees, rarely shrubs: branches with lamellate pith: lvs. alternate, without stipules, odd- pinnate, of aromatic fragrance when bruised: staminate fls. with a 2-5-lobed perianth and 6-30 stamens, in slender catkins; pistillate fls. in few- to many-fld. racemes; ovary inferior, 1-celled, with 4 calyx-lobes and included in a 3-lobed involucre: fr. a large drupe with a thick, indehiscent husk; nut 2- or 4-celled at the base, indehiscent or separating at last into 2 valves. —About 15 species in N. and S. Amer. and from S. E. Eu. to E. Asia; 44 species have been distinguished and described in a monograph by Dode (B.S.D. 1906: 67-97; 1909: 22-50, 165-215, with many illustrations). The walnuts are usually tall broad-headed trees with large leaves, and with small greenish flowers, the staminate in pendulous slender often conspicuous catkins, the pistillate inconspicuous followed by a greenish large drupe containing an edible nut. Most of the species are hardy, and are very valuable park trees, with a massive, straight trunk, and a light and airy broad top, the best being probably J. nigra, one of the noblest trees of the American forest. J. regia, J. rupestris, and J. cathayensis are hardy as far north as Massachusetts, while J. californica is tender in the North. Though many fungi and insects prey on the walnut, none of them does very serious damage, the worst being, perhaps, the hickory-borer. The wood of the walnut, which is easily worked and susceptible of receiving a beautiful polish, is much used for cabinet making and the interior finish of houses, especially that of J. nigra and J. regia, which is heavy, strong and durable, and of dark brown color, while that of J. cinerea and J. Sieboldiana is light and soft. The husks of the nuts are sometimes used for dyeing yellow, and the bark for tanning leather. The husk of J. cinerea has some medicinal properties. The nuts of all species are edible, and are an article of commercial importance, especially those of J. regia, which are the best. This species is extensively grown in the warmer parts of Europe, in California and in the East from Pennsylvania to Georgia. The nuts of the native species are also sold on the market, but mostly gathered in the woods, though a number of improved varieties are in cultivation. J. sieboldiana and var. cordiformis, with nuts superior to those of the native species, and much valued in Japan, will probably become valuable nut trees where J. regia is too tender; also J. regia var. sinensis is hardier than the type. The walnut grows best in moderately moist, rich soil, but J. cinerea is more moisture-loving and J. regia prefers well-drained hillsides. They are not easily transplanted when older, and therefore the nuts are often planted where the trees are to stand, but they may be safely transplanted when two or three years old, or even later when they have been transplanted in the nursery. Propagation is by seeds, which should be stratified and not allowed to become dry. A light, sandy soil is to be preferred, as the young plants produce more fibrous roots, while in stiff soil they are liable to make a long taproot. The young seedlings are transplanted when about two years old; sometimes the taproot is cut by a long knife. Varieties are often grafted on potted stock in the greenhouse in early spring or are budded in summer, either shield- or flute- budding being employed; even top-grafting of old trees is sometimes practised. For culture and further information, see United States Department of Agriculture, "Nut Culture in the United States," quoted below as U. S. N. C.; see, also, Walnut. Index. ailantifolia, 10. alata, 12. allardiana, 10. aspleniifolia, 1. bartheriana, 1. californica, 4, 5. cathayensis, 8. cinerea, 7. coarctata, 10. corcyrensis, 1. cordiformis, 10. draconis, 8. duclouxiana, 1. elongata, 1. fertilis. 1. filicifolia, 1. fruticosa, 1. gibbosa, 11. hindsii, 5. intermedia, 11, 12. laciniata, 1. lavallci, 10. major, 2. mandshurica, 9. monophylla, 1. nigra, 6. ovoidea, 6. pendula, 1. praeparturiens, 1. pyriformis, 11. quadrangulata, 12. quercina, 5. quercifolia, 5. regia, 1. rupestria, 2, 3. sieboldiana, 10. sinensis, 1. subcordiformis, 10. torreyi, 2. vilmoreana, 11. vitmoriniana, 11. Besides these described above, several other hybrids have been reported. Luther Burbank raised a hybrid between J. hindsii and J. nigra, named "Royal," with large nuts of excellent flavor, and one between J. Hindsii and J. regia, named "Paradox," a very vigorous grower, but a shy bearer. There are supposed hybrids between J. mandschurica X J. regia, J. cinerea XJ. nigra and J. cinerea X J. rupestris; J. longirostris, carr. (R. H. 1878, p. 53), may be a hybrid between J. regia and J. major, which often has a fr. similar in shape to the one figured.—J. australis. Griseb. Allied to J. rupestris. lfts. 13-21, large, ovate-oblong, abruptly acuminate, serrate, viscid- pubescent: nut ovoid, acute, small, slightly grooved. Argentina.— J. collapsa, Dode. Allied to J. mandschurica and probably only a variety, but nut less rugose, less sharply angled, with ovoid depressions. Probably from N. China.—J. kamadnia, Dode (J. regia var. kamaonia, DC.). Allied to J. regi. Lfta. 5-11, oblong-elliptic to oblong-lanceolate, puberulous on both sides, rufous-pubescent on the veins beneath: nut globose, rather hard-shelled. Himalayas. —J. stenocorpa, Maxim. Closely allied to J. mandschurica. Lfts. narrower, more coarsely serrate, more pubescent, the terminal 1ft. very large: fr. more oblong, less strongly ridged. Manchuria. Alfred Rehder The above text is from the Standard Cyclopedia of Horticulture. It may be out of date, but still contains valuable and interesting information which can be incorporated into the remainder of the article. Click on "Collapse" in the header to hide this text.

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References

• Standard Cyclopedia of Horticulture, by L. H. Bailey, MacMillan Co., 1963

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