"The jujube" writes David Fairchild, "is one of the five principal fruits of China, and has been cultivated for at least 4000 years." It is only in the large-fruited Chinese varieties that the jujube is seen at its best. The inferior fruits which have been grown in southern Europe, Arabia, and northern India either represent a different species from those of China, or are varieties which have not been so highly improved by cultivation and selection.
Pliny recounted that the jujube was brought from Syria to Rome by the consul Sextus Papinius, towards the end of the reign of Augustus. It has, therefore, been known in southern Europe for more than 2000 years. It reached America some time during the nineteenth century, but only in the form of seedlings which yielded fruit of poor quality. With the introduction of the grafted Chinese varieties, obtained in 1906 and subsequent years by the United States Department of Agriculture, the jujube has become a fruit-tree worthy of the serious attention of horticulturists, and this it is now receiving throughout the southern and western parts of the United States. The botany of this fruit is decidedly confused. Two species are cultivated in the Orient, differing but little from each other in botanical or horticultural characteristics. The Chinese jujube (Fig. 50) is considered to be Zizyphus Jujuba, Miller (Z. vulgaris, Lam., Z. sativa, Gaertn.), and the Indian jujube, Zizyphus mauritiana, Lam. (Z. Jujuba, Lam.). The principal difference between them seems to be that the leaves of the first-named are glabrous while those of the second are tomentose beneath. Further study will be required to show the proper classification of many cultivated forms.
Fig. 50. The lang tsao, or "melting jujube" (Ziziphus Jujuba), from the Province of Shensi, China, now grown in California. The Chinese varieties of the jujube are better than those of other countries. (X 3)
The jujube is a small, somewhat spiny tree reaching a height of 25 or 30 feet. Its leaves are alternate, three-nerved, elliptic-ovate, ovate, or suborbicular in outline, commonly 1 1/2 to 3 inches in length. The small greenish flowers are produced upon slender deciduous branchlets, or occasionally upon the old wood. The fruit is a small drupe, elliptic or oblong to spherical in form, from 1/2 to 2 inches in length, with a thin dark brown skin, and having whitish flesh of crisp or mealy texture and sweet agreeable flavor, inclosing a hard two-celled stone, elliptic to oblate in form and rough on the surface.
In searching botanical literature for data regarding the history and distribution of the jujube, it is impossible to determine, in many cases, whether Z. Jujuba or Z. mauritiana is the species discussed. One or the other (probably both in some instances) is cultivated in China, in the Philippines, through the Malayan region to India and Africa, and westward through Afghanistan, Persia, Arabia, and Asia Minor to the Mediterranean coast of France, Spain, and North Africa. In China the general name is tsao; in India Z. Jujuba is called the common jujube, anab, un-nab, while Z. mauritiana is called the Indian jujube, ber, bor, and the like. In Arabia the common term for one species is nabk.
The late Frank N. Meyer, to whom we are indebted for many fine Chinese varieties of this fruit, observed, during his explorations in China, that the jujube could be used in several different ways. The fresh fruits of some varieties are excellent to eat out of hand. Dried, they resemble dates in character. Jujubes are sometimes boiled with millet and rice; they may be stewed or baked in the oven; they are used, raisin fashion, to make jujube-bread; and they are turned into glace fruits by boiling them in honey and sugar sirup. Meyer particularly lauds the mi-tsao, or honey-jujube. "To prepare this," he says, "the Chinese take large, sound, dried fruits and boil them thoroughly in sugared water, after which they are taken out and dried in the sun or wind for a couple of days. When sufficiently dry they are given a slight boiling again and are partly dried. When dry enough to be handled, the skin is slightly slashed lengthwise with a few small knives tied together. Then the fruits are given a third boiling; now, however, in a stronger sugar water, and for the best grades of honey-jujube honey is added. When this process is finished they are spread out to dry, and when no longer sticky are ready to be sold."
A chemical analysis of the Chinese jujube made by the Bureau of Chemistry at Washington showed it to contain: Total solids 31.9 per cent, ash 0.73, acids 0.29, protein 1.44, total sugar 21.66 (sucrose 9.66, invert sugar 12.00), fat 0.21, hydrolyzable carbohydrates 2.47 and fiber 1.28.
Regarding the climatic and soil requirements of the jujube, Fairchild l writes:
"No weather appears to be too hot for it, and so far as resistance to cold is concerned, it has withstood temperatures of 22° F. without injury. Just how much lower winter temperatures it will withstand has not yet been determined. The range of territory, however, over which it is likely to prove a success as a fruit tree will probably be limited more by the length of the summer season than by the severity of the winter. The whole Southwest, with the exception of the elevated areas where cold summer nights occur ... is a promising region in which to test the jujube. It enjoys brilliant sunshine, dry weather, and long, intensely hot summers, and although it will form good sized trees under other conditions, it appears to require these climatic factors to make it fruit early in life, regularly, and abundantly.
"As regards soil conditions, it appears to withstand slight amounts of alkali and to thrive with special vigor on the loess, or wind-drifted soil formations of China. . . . Under irrigation in northern California, and without irrigation in Central Texas, the trees have grown luxuriantly and fruited abundantly. In the warm humid region of Maryland, seedling trees have grown well, but fruited sparingly and irregularly. In Georgia, old seedling jujubes have fruited well."
1 Journal of Heredity, Jan., 1918.
R. L. Beagles 1 says: "The jujube has endured a temperature of 13° F. at the Chico Station without any perceptible injury; it also withstands extreme heat, a temperature of 111° F. producing no apparent bad effects on trees and young grafted plants. . . . The tree starts into growth very late in the spring, which eliminates any danger from frost, and makes it a sure cropper. The fruits ripen in October and November."
Meyer 2 writes regarding the cultivation of the jujube in China:
"In general, jujubes are grown in small groves or as single trees, but here and there one also meets regular orchards of them, covering perhaps 10 or 20 acres. In some localities the farmers plant them in rows through the fields. It seems that planted in this way, at a distance of five to ten feet apart, they produce the largest quantity and best quality of fruit. When in regular orchards the distance apart is from 15 to 25 feet, depending upon the variety and upon the personal preference of the planter.
"The farmers, here and there, also have the practice of ringing their trees every year, claiming that thereby they considerably increase the crop. The jujube is about the only fruit tree around the roots of which the soil is not regularly cultivated, because the yield is found to be just as large without this work as with it."
Propagation is effected by seeds, grafting, root-cuttings, and one or two other means. Meyer reports regarding the methods employed in China: "As the varieties do not come true to seed, the trees are mostly propagated by the suckers which are nearly always found at their bases. Root cuttings can also be taken. Some varieties, however, do not readily produce suckers, and root cuttings are not successful. Then the Chinese resort to grafting the cions on wild stock. This grafting practice, however, seems to be confined to only a few localities, where the growers are men of considerable experience."
1 California Citrograph, Oct., 1917. 2 Bull. 204, Bur. Plant Industry.
The most satisfactory method of propagating the Chinese varieties in California has been whip-grafting. Seedling jujubes are used for stock-plants. These are easily grown, although the seeds (which are sown in drills in the open ground) are slow to germinate and it takes two years to produce a good plant. At one year of age many of them will be large enough to graft, but it is better to leave them until the second year.
J. E. Morrow, who has had experience in propagating the jujube at the United States Plant Introduction Field Station at Chico, California, notes that plants grafted in February sometimes grow to a height of three or four feet before the end of the year and mature a few fruits. He says further:
"The jujube root is one which does not like to be disturbed, and for quick results, and where climatic conditions will permit, I would advocate field-grafting on two-year-old roots. The cions are inserted close to the root, and covered with soil, which should not, however, be over one inch in depth above the top of the cion, so that when the ground settles after a hard rain the young plant will still be able to force its way through it.
"The argument in favor of bench-grafting is this: it may be done when the soil is too muddy or cold to permit outside work. The stock-plants are cut off just above the root, or the larger roots themselves are used as stocks. Upon these a cion about four inches long and of the diameter of a lead penicl is whip-grafted, and wrapped with raffia. A wedge-graft may be used if the stock is much larger than the cion. The grafts are then packed in boxes, between layers of moistened cedar or redwood sawdust or ' shingletow.' The box should be kept where temperature remains between 40° and 50°. In about a month calluses should have formed, and the grafts may be planted in the field. Grafting may be done in California any time in February or March, and the plants should go into the field not later than April 1. Cions may be cut between the first of December and the first of February, and stored until wanted for use."
The jujube is precocious and prolific in fruiting, and rarely fails to produce a good crop. Meyer observed in China that the plants begin to decline in vigor and productiveness after twenty-five or thirty years, and rarely live more than forty years. There are many varieties known in China, and not a few in other countries. Meyer has described ten of the best Chinese kinds in Bulletin 204, quoted above: most of these have been introduced into the United States and some have already produced fruit here. The best are considered to be the Yu, the Mu shing hong, and the Lang.