From the Manual Of Tropical And Subtropical Fruits
by Wilson Popenoe
The Jujube
Zyzyphus spp.
"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 the langtsao, or "melting jujube" (Ziziphus Jujuba), from the Province of Shensi, China, now grown in Cahfornia. The
Chinese varieties of the jujube are better than those of other
countries. 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 is
considered to be Zizyphus Jujuba, Miller (Z. vulgaris, Lam., Z. saliva, 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.
The jujube is a small,
somewhat spiny tree reaching a height of 25 or 30 feet. Its leaves are
alternate, three-nerved, ellipticovate, ovate, or suborbicular in
outline, commonly 1 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 I 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. Jujuha 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, anah, unnah, while Z. mauritiana is called the Indian jujube, her, hor, and the like. In Arabia the common term for one species is nahk.
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 1 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 less, 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.
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 stockplants 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.
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