The Japanese, who cultivate more than 800 varieties of the kaki, consider it one of their best fruits. The Chinese also value it highly and devote large areas to its production. Although it has been grown on a small scale in southern France for nearly a century, it is not believed to have reached the United States until the time of Commodore Perry's visit to Japan in 1856, and it was only in 1870 (or thereabouts) that grafted trees of superior varieties were first brought to this country.
Much attention has recently been devoted to the kaki, and it seems probable that it will assume an important position among the orchard-fruits of the cotton-belt and of California. If it does so, credit for its establishment on such a basis will be due largely to the United States Department of Agriculture as having introduced into this country the best Chinese and Japanese sorts, and to H. H. Hume of Florida for his investigations of cultural problems. The name of Frank N. Meyer, late agricultural explorer for the Department of Agriculture, will be remembered by horticulturists in connection with the introduction of Chinese varieties.
The kaki is a deciduous tree growing up to 40 feet in height (though there are dwarf varieties which remain smaller than this), and having usually a round open crown. The leaves are ovate-elliptic, oblong-ovate, or even obovate in outline, acuminate at the apex, glabrous above and finely pubescent beneath, and 3 to 7 inches long. While it has usually been supposed that the kaki is dioecious, or rarely polygamous, Hume 1 has shown that a single tree may produce three kinds of flowers, perfect, staminate, and pistillate, in varying combinations. All of these are borne upon the current season's growth and open shortly after the shoots and leaves are developed. Staminate flowers are borne in three-flower cymes in the leaf-axils; the calyx and corolla are four-lobed and the latter has sixteen to twenty-four stamens inserted upon it in two rows. The pistillate flowers are solitary and axillary and have a large leaf-like calyx, a four-parted light yellow corolla, eight abortive stamens, and a flattened or globose, eight-celled ovary surmounted by a short four-parted style and much-branched stigma. Perfect flowers are intermediate in character between the staminate and the pistillate, and are most commonly associated with the former. Hume says: "Up to this time they have not been discovered on any varieties of the fixed pistillate-flowering type. In other words, it appears that the perfect flowers are a development from the staminate form and not from the pistillate form." It may be observed that the kaki corresponds in this respect to the papaya, in which perfect flowers are sometimes developed on trees which are normally staminate but never on those which are pistillate.
1 Trans. St. Louis Acad. Sci., XXII, 5, 1913.
The fruit is oblate to slender conic in form, and from 1 to 3 inches in diameter. It has a thin membranous skin orange-yellow to reddish orange in color; soft (sometimes almost liquid) orange-colored pulp of sweet and pleasant flavor; and occasionally as many as eight elliptic, flattened, dark brown seeds, although there are frequently not more than half that number, and seedless fruits are of common occurrence.
The kaki was formerly thought a native of Japan, but it is now understood that it was originally confined to China, whence it was carried to Japan several centuries ago. Hume believes that the cultivated kakis may be derived from more than one wild species. This theory was suggested by the different reactions of certain varieties to the stimulus of pollination. After describing these reactions 1 he asks:
"Why is it that D. kaki presents these peculiar characteristics? Why is it, for instance, that Tsuru is always light fleshed whether the fruit contains seeds or not, while Yemon is light fleshed when seedless and dark fleshed when seedy? Is it not likely that D. kaki is not a true species but rather a mixture of two or more species, hybridized and grown under cultivation for centuries? Is it not possible that the present cultivated varieties known under the name of D. kaki are derived from two distinct species, one bearing dark fleshed fruit and the other light fleshed fruit? ... In shape and peculiarities of fruit, color and characteristics of bark, size and shape of leaves, habit of growth and size of tree, they vary much more than any of our common fruits usually regarded as being derived from a single species."
From Japan the kaki has been carried around the world. Its cultivation in France has already been mentioned; it is limited principally to the Cote d'Azur (the Riviera) and Provence. On the opposite shore of the Mediterranean, in Algeria, it is grown to a limited extent. It has never been cultivated widely in India, but A. C. Hartless reports recently that certain varieties have proved successful at Dehra Dun and elsewhere, and grafted plants are being disseminated from the Botanical Garden at Saharanpur. In Queensland, where it is said to have been introduced less than forty years ago, it is meeting with favor but is not yet extensively grown. In the United States it has been planted chiefly in Florida, Louisiana, and California.
1 Journal of Heredity, Sept., 1914.
The name kaki, which is applied to this fruit in Japan, has become current in the United States and in southern France. Japanese persimmon and occasionally date-plum and Chinese date-plum are terms used in the United States, and plaquemine in France. The Chinese name is shi tze. Botanically the cultivated kakis are commonly grouped together under the name Diospyros Kaki, L. f., of which D. chinensis, Blume, D. Schitse, Bunge, and D. Roxburghii, Carr., are considered synonyms. French botanists have made botanical varieties or even species out of some of the forms which are elsewhere held to be mere horticultural varieties, e.g., costata.
In the United States the kaki is usually sold as a fresh fruit, to be eaten out of hand. In Japan certain varieties are used extensively for drying, the product somewhat resembling dried figs in character and being delicious. "The method of drying," writes George C. Roeding, "is simple. The skin is pared off and the fruits are suspended by the stems, tying them with string to a rope or stick and exposing them to the sun. They gradually lose their original form, turn quite dark and are covered with sugar crystals. . . . Fruit should be picked for drying when yellow and firm."
Methods of processing the mature fruit, so as to remove its astringency, are discussed on a later page. The chemical composition of five varieties is shown in the following table, from analyses made by H. C. Gore: