Although 800 varieties are grown in Japan, Ikeda does not consider more than 90 to be valuable. In the United States the number offered by nurserymen is relatively small. The nomenclature of the horticultural varieties in Japan is somewhat confused, and doubtless nurserymen have multiplied the names. China possesses a considerable number of varieties, but relatively few of them are yet known in the United States.
Japanese writers classify kakis according as they are sweet or astringent. Hume points out that such a classification is not tenable, inasmuch as certain varieties fall in the sweet group when carrying seeds and in the astringent group when seedless. He writes in the Journal of Heredity for September, 1914:
"Based on the difference in flesh coloration under the influence of pollination, kaki may be divided into at least two groups, - first, those which show no change of color of flesh under the influence of pollination, and, second, those in which the flesh of the fruit is darkened under the influence of pollination. Since the change in color in the one case is directly due to pollination and in the other pollination has no effect whatever, we shall refer to those varieties which undergo no change in color as Pollination Constants and those which are light colored when seedless and dark colored when seedy we shall call Pollination Variants. Now, all varieties of D. kaki growing in this country or elsewhere may be referred to one or the other of these groups. If varieties which are constantly dark-fleshed whether seedy or seedless should be found, the group of Pollination Constants can then be divided into two groups of light- and dark-fleshed Pollination Constants. It is hardly probable that there are varieties which are dark-fleshed when seedless and light-fleshed when seedy, but if any such should be discovered a similar plan can be followed by dividing the group of Pollination Variants."
The varieties here described are grouped according to this classification. The number is limited to those which are well known in the United States, and are offered here by nurserymen. Regarding their relative merits, Hume says: "Tane-nashi, Triumph, Okame, Yemon, and Yeddo-ichi excel in quality, perhaps in the order named. Okame, on account of its long season, exquisite beauty, and superior quality, is the best for home use and the local market. Hachiya is valued for its immense size and showiness. For market, Tane-nashi and Yemon, of the light-fleshed kinds, and Hyakume and Yeddo-ichi, of the dark-fleshed kinds, are good shippers and desirable; Okame is also good." Fuyugaki, a variety recently introduced by the Department of Agriculture, now promises to excel all other kakis as a market fruit; it is never astringent (hence requires no processing), the appearance and quality of the fruit are both highly satisfactory, and the tree is very productive.