As one might suspect from its similarities to the several stone-fruits, Prunus davidiana gives promise of being a go-between in hybridization. I. V. Mijurin, a noted Russian hybridist of Kozloo, Russia, has crossed the Davidiana peach and the dwarf almond, Prunus nana, with the idea of getting a hardy fruit for central Russia. The resulting offspring, according to Mr. F. N. Meyer,[179] looks in tree like the peach-parent but the fruit is more like that of the almond-parent. The fruit of the hybrid is inedible but the plant is a handsome ornamental. Mr. Mijurin states that while neither of the two parents will hybridize with the common peach, this hybrid does. Prunus davidiana, then, like the Sand Cherry of the Western Plains, may prove to be a valuable go-between in hybridizing species of Prunus.
The fruit has no comestible value. It is small, less than an inch in diameter, nearly round, very downy, yellow at maturity, with thin, dry, tasteless flesh which parts readily from the stone even before fully ripe. As if to complete its worthlessness as an edible product, it begins to shrivel as maturity approaches and soon decays. In fruit, even more than in tree, it is an intermediate between the peach and the almond.
A word must be said as to the merits of Prunus davidiana as an ornamental. It is the first harbinger of spring in the great family to which it belongs, bursting into a profusion of white or pinkish flowers with the approach of warm weather even before forsythias are in flower. Its thickly set, erect branchlets are wands of pinkish-white two feet in length, making a handsome tree and furnishing beautiful cut-flowers. If grown for its flowers, however, one must be content in northern climates to have it in bloom only about one season out of three but even so it repays culture. The Chinese cultivate dwarf specimens, possibly a dwarf form, for winter-flowering and the plant, it would seem, would readily lend itself to winter-forcing in American floriculture. The tree, quite aside from its flowers, is handsome at all times. A form with pure white flowers is a very desirable ornamental.[180] On the Station grounds this white-flowering peach has a fastigiate habit of growth and resembles somewhat a small Lombardy poplar.
PRUNUS MIRA Koehne.
P. mira Koehne Plant. Wilson. Pt. 2, No. 4:272. 1912.
Tree thirty feet in height; trunk sixteen inches in diameter; branches very smooth, those of the current year's growth green, the older ones dark reddish-yellow; flowering-season short; stipules lacking or obscure; petioles five-sixteenths to ten-sixteenths of an inch long, with from two to four glands toward the apex, the glands broadly elliptical, disc-shaped; leaf at the base usually roundly lanceolate, two to four inches long, nine-sixteenths to one and one-sixteenth inches broad, gradually narrowing toward the apex; margin broadly crenulate-serrulate, tapering upward without division; teeth crowned with small, soot-colored, mucronate glands; upper surface clear green, glabrous; lower surface paler, villous along both sides of the lower ribs and the rest glabrous; veins on both sides twelve to sixteen, the veinlets somewhat raised on the under side.
The pedicels of the single or twinned fruits two-sixteenths to three-sixteenths of an inch long, very thick, glabrous; drupes somewhat dry, sub-globose, one and one-eighth inches long, one inch in diameter, densely tomentose, edible; stone ovate, somewhat compressed, dimensions three-fourths by one-half by three-eighths inches; dorsal suture keeled, the ventral surface covered with narrow ridges, the ridges at the base of the keel nearly disappearing, the rest inconspicuous.
Prunus mira is a new peach discovered in China by Mr. E. H. Wilson of the Arnold Arboretum. The foregoing technical description is a translation from the original description by Koehne. Mr. Wilson describes for The Peaches of New York the outstanding botanical and horticultural characters of Prunus mira as follows:
"Prunus mira is a small bushy tree, growing about 6m. tall, with a trunk about 1m. in girth and a crown some 8m. through. The branches are relatively slender and the branchlets twiggy, and these, together with the narrow, lance-shaped, long-pointed leaves, give the plant a very distinct appearance. The fruit is roundish oval, about 4.5 cm. high and 3.5-4 cm. broad, downy on the outside, with white flesh and a free stone. The flavor is the same as that of fruits from the semi-wild plants of the Common Peach (P. Persica). The stone is 2 to 2.2 cm. high and 1.3-1.4 cm. broad, and in shape is flattened ovoid and pointed. The flowers are unknown to me.
This plant grows wild on rather barren mountain slopes at about 3000m. altitude north of the town of Tachienlu on the China-Thibetan borderland, where it was first detected by me on July 9, 1908, and from whence I introduced it by means of seeds in the autumn of 1910. I saw only a few trees, but have reason to believe that it is fairly common, and also that it is thereabouts cultivated for its fruit. In the Arnold Arboretum this species has proved no more hardy than the Common Peach, though from the altitude at which it grows naturally it ought to be the hardier plant. Our largest specimen is 2.5m. high and crown 3m. through. It starts into growth and leafs out much later than the Common Peach, and is therefore much less liable to be affected by late frosts. This is the one advantage so far evident in our experience with this new Peach under cultivation. Undoubtedly it possesses important horticultural possibilities, and especially should it be valuable to the hybridist on account of its small and smooth stone. Indeed, it requires no imagination to realize the advantage to be gained by supplanting in our present day race of garden peaches for the large and deeply furrowed stone one that is quite smooth and small."
Prunus mira is now under cultivation at the Arnold Arboretum near Boston, in the parks at Rochester, New York, on the grounds of this Station and at Brookville, Florida, in charge of the United States Department of Agriculture. No doubt within a few years we shall have positive evidence of its horticultural value.