The yellow plums of the Roman poets, Ovid and Vergil, are probably the Bullaces or Mirabelles of this species. Indeed, its cultivation was probably prehistoric, for Heer[67] has illustrated and described stones of a plum found in the lake-dwellings of Robenhausen which can be no other than those of Insititia.

The authentic written history of this plum may be said to have begun with or a little before the Christian Era. The records of the cultivation and development through the early centuries of the present chronology and the Middle Ages to our own day may be found in the herbals, botanies, pomologies, agricultural and general literature of the past two thousand years.

Prunus insititia now grows wild in nearly all temperate parts of Europe and western Asia—from the Mediterranean northward into Norway, Sweden and Russia. The botanists of Europe very generally agree that its original habitat was in southern and southeastern Europe and the adjoining parts of Asia, and that elsewhere it is an escape from cultivation. Hooker[68] says that Prunus insititia grows in western temperate Himalaya, cultivated and indigenous, from Gurwhal to Kashmir, the type being that of the “common yellow-fruited Bullace.” A few botanical writers hold that it is truly wild in the parts of Europe where now found growing. There are also not a few botanists who, as has been stated in the discussion of the Domestica plums, unite the Insititias with the Domesticas, and others who combine these two with the Spinosa plums in one species, Prunus communis.[69]

It is possible that the species is occasionally found naturalized in eastern United States; several botanists so give it.

Wherever the habitat of the Insititia plums may have been, practically all writers from the Greeks and Romans who first mention this fruit to those of the present time, connect the cultivated varieties in one way or another with the old Semite city, Damascus. It is almost certain that the Syrians or Persians were the first to cultivate these plums, and that they were unknown in Europe as domesticated varieties until the Greeks first and the Romans afterward came in intimate contact with the people of the Orient. Thus it is often stated in the old pomologies that Alexander the Great brought these plums from the Orient after his expedition of conquest and that some centuries later Pompey, returning from his invasion of the eastern countries, brought plums to the Roman Empire.

The history of the Insititia plums in America has been given in the main in the discussion of the Domestica plums, for the varieties of the two species have never been kept separate by plum-growers, all being grouped together as European plums. It is probable, however, that the Damson plums of this species were earlier introduced and more generally grown than any other of the European plums by the English settlers of America, as the references to plum-growing before the Revolution are largely to the Damsons. The reasons for this early preference for these plums are that they come true to seed while most varieties of the Domestica do not; and trees and cions were not readily transportable in colonial times; and, too, the Damsons have always been favorite plums with the English.

When the first American fruit books were published at the beginning of the Nineteenth Century the Damsons and Bullaces were widely grown, for all writers give a relatively large number of varieties of these plums and speak well of them. Thus McMahon,[70] in his list of thirty plums gives six that belong here, ending his list with “Common Damson, etc.,” as if there were still more than those he enumerates. Prince, in his Pomological Manual, in 1832, gives at least eighteen sorts that may be referred to Insititia with the statement that one of them, the Early Damson “appears to have been brought to this country by the early Dutch settlers, or by the French who settled here at the time of the revocation of the Edict of Nantes,” adding, “It is much disseminated throughout this section of the country.” At the end of the Eighteenth Century Deane’s[71] New England Farmer or Georgical Dictionary, in a discussion of plums in general says: “The most common plum in this country is the Damascene plum, an excellent fruit for preserving, which is said to have been brought from Damasam, hence the name.”

The hardiness, thriftiness and productiveness of all of the varieties of this species commend them to those who cannot give the care required to grow the less easily grown Domesticas, and in America, as in Europe, these plums are to be found in almost every orchard and in many communities half-wild, thriving with little or no care. The fact that they are easily propagated, growing readily from suckers and coming true to seed is an added reason for their general distribution.

The Insititia plums do not seem to hybridize freely with other species—at least there are no recorded offspring of such hybrids, though Koch believes the Reine Claudes to be a hybrid group between this species and the Domesticas and there is much evidence in the fruit to show that the French Damson is part Domestica. The tree-characters of the Insititia plums are such, especially as regards vigor, hardiness, productiveness and freedom from disease, as to seemingly make hybrids with them very desirable. That this species can be hybridized with Domestica, at least, is certain from work done at this Station where we have made a number of crosses between them.

Four groups of plums, the Damsons, Bullaces, Mirabelles and St. Juliens, in all eighty-six varieties mentioned in The Plums of New York, may be referred to this species. There are so few real differences between these divisions, however, that it is hardly possible, logically, to sub-divide Insititia plums into more than two groups. But since the groups of plums given above are so often referred to in pomological works it is necessary to discuss them.

The Damsons.—The description given the species fits this division of it closely, the differentiating character for the fruit, if any, being oval fruits, while the Bullaces, most nearly like these, are round. The origin of the Damsons, as we have seen, was in Syria and near the ancient city, Damascus, their written history dating back several centuries before Christ. This plum has escaped from cultivation in nearly all the temperate parts of Europe and more or less in the eastern United States, the wild forms often passing under other names, as the Wild, Wheat, Spilling, Donkey, Ass, Hog and Horse plums. The true Damsons have a fine spicy taste, which makes them especially desirable for cooking and preserving, but a very decided astringency of the skin makes most of the varieties of Damsons undesirable to eat out of the hand; this astringency largely disappears with cooking or after a light frost. Nearly all Damsons are sour, though a few sweet Insititias are placed in this group.

Since the seeds grow readily and the sprouts are very manageable, the Damsons, with the other Insititias, are much used as stocks upon which to work other plums, especially the less hardy and less thrifty Domesticas. Although less used now than formerly for stocks it is a question if these plums, or some of their near kin, do not make the best obtainable stocks. There seems to be much difference in the varieties of Insititia in their capacity to send up sprouts. The forms which send up the fewest sprouts are much the best for use as stocks.

Curiously enough, the Damsons are highly esteemed now only by the Americans and English, being grown much less at present in Continental Europe than a century or two ago. Late pomological works and nurserymen’s catalogs from others than the English or Americans barely mention these plums.

The Bullaces.—It is impossible to distinguish between the tree-characters of the Damsons and the Bullaces, and pomologists are far from agreeing as to what differences in the fruit throw a variety into one group or the other. Some writers call a sour variety of Insititia a Damson, and a sweet one a Bullace; others make color the differentiating character, calling the purple plums Damsons and the light colored ones Bullaces; still others call oval Insititias Damsons and round ones Bullaces. If a distinction is to be made, shape seems to be the character upon which it should be based. The name Bullace applies to the round shape of the fruit, but when first used or by whom given it is impossible to say. It is commonly used in the old herbals and pomologies of both England and Continental Europe, there being many variations of the name, of which bullis and bulloes are most common with the word bullum in frequent use for the fruit of the Bullace tree. The varieties of Bullaces are few in number, and are not largely grown, being known for most part only in fruit collections, the Damsons serving all the purposes for which the Bullaces would be worth growing, and to better advantage.

The Mirabelles.—The Mirabelles are round, yellowish or golden, freestone Insititias, ranging from half an inch to an inch in diameter, very slightly sub-acid or sweet. The trees do not differ from the type of the species unless it be in even greater productiveness than the other groups of Insititia, all of which bear very abundant crops. The fruits represent the highest quality to be found in the varieties of this species, approaching the Reine Claudes of Prunus domestica in richness of flavor. Indeed, the Mirabelles may almost be said to be diminutive Reine Claudes, resembling them not only in quality but in color and in shape, and so closely as to lend color to Koch’s[72] supposition that the Reine Claudes are hybrids between Prunus domestica and Prunus insititia.

In France the Mirabelles are accorded second if not first place among plums, being superseded in popularity, if at all, only by the Reine Claudes. They are used in the fresh state and as prunes, and are freely made into conserves, preserves, jellies and jams, being found in the markets in some of these forms the year round. They are much used for pastry, their size being such that one layer of fruit suffices and is none too deep for a good pie or tart. The fermented juice of these plums is somewhat largely used in the making of a distilled liquor, a sort of plum brandy. The dozen or more varieties of Mirabelles differ chiefly in size of fruit and in time of maturity. The range in size is from half an inch to an inch in diameter and in time of ripening in France from the first of August to the first of October.

The Red Mirabelle frequently referred to in pomological works is Prunus cerasifera, and the name is wrongly so used, for if not first applied to the several varieties of Insititia it now by almost universal usage belongs to these plums. The origin of the word, as now commonly used, dates back over two centuries, being found in the pomological treatises of the Seventeenth Century. The assumption is that Mirabelle is derived from mirable meaning wonderful, and the name was first so used by the French.

Unfortunately the Mirabelles are hardly known in America. These plums have so many good qualities of tree and fruit that American pomology would be greatly enriched if the best Mirabelle varieties were grown in both home and commercial orchards. They should be used in cookery much as are the Damsons, which they surpass for some purposes.

St. Juliens.—The St. Julien that the writer has seen in American and European nurseries is unmistakably an Insititia. At one time St. Julien stocks were used almost exclusively in New York nurseries, and few large plum orchards are free from trees which have through accident to the cion grown from the stock. Such trees bear fruit so like the Damson that one is warranted in saying that the two are identical, and that St. Julien is but a name used for a Damson when the latter is employed as a stock. The fruit is sweetish with a taste identical with that of the sweet Damsons.

Plum-growers who have had experience with plums on several stocks are almost united in the opinion that the St. Julien is the best of all for the Domesticas, at least. St. Julien stocks were formerly imported in great numbers from France, where it is still largely grown for European use. The name seems to have come in use in France more than a century ago, but why given or to what particular Insititia applied does not appear. There is, however, a distinct variety or type of Insititia used by the French in producing stocks, for French pomologists advise careful selection of mother-plants for the production of the young trees by suckers or layers, and caution growers of stocks in no case to use seeds which bring twiggy, spiny and crooked stocks.[73] St. Julien plums are seemingly nowhere grown at present for their fruits.

There are several ornamental forms of plums which are given specific names by European horticulturists, mentioned in the last paragraph in the discussion of the Domestica plums, which some writers place, in part at least, with the Insititias. These plums are not found in America and it is impossible to place them with certainty in either of the two species upon the contradictory evidence of the Europeans.

3. PRUNUS SPINOSA Linnaeus.

European botanists commonly break the species into a number of sub-species, as:—Prunus spinosa typica Schneider,[74] flower-pedicels and calyx-cup glabrous; Prunus spinosa praecox Wim. and Grab.,[75] pedicels short, blossoms appearing before the leaves; Prunus spinosa sessiliflora Beck,[76] with sessile flowers, possibly the same as the next preceding form; Prunus spinosa coatanea Wim. and Grab.[77], blossoming with the leaves and with long pedicels; and Prunus spinosa dasyphylla Schur.[78], flower-pedicel and calyx-cup more or less hairy. Besides these botanical sub-divisions there are several horticultural forms as follows:

Prunus spinosa flore-pleno of the nurserymen is a double-flowered form, making a beautiful little shrub or small tree much planted in gardens in Europe and somewhat in America. Its blossoms are pure white, about half an inch in diameter and not quite double, as the stamens form an orange cluster in the center of the flower. The flowers are thickly crowded on short spiny branches, the dark color of which forms a striking contrast to the white flower. Prunus spinosa purpurea is another horticultural group, more vigorous than the species, less thorny and with larger foliage. Its branches are erect, purplish in color, striated. The leaves and petioles are at first very pubescent but at maturity glabrous; the upper surface of the leaf is green marked with red, the under a deep reddish-violet. The flowers are a pale rose. One or two variegated forms of this species are also offered by nurserymen.

Schneider holds[79] Prunus fruticans Weihe[80] and Prunus spinosa macrocarpa Wallroth[81] to be crosses between Prunus spinosa and Prunus insititia.

Prunus spinosa, the Blackthorn or European Sloe, is the common wild plum of temperate Europe and the adjoining parts of Asia. It is adventive from Europe to America and is now quite naturalized along roadsides and about fields in many places in eastern United States. Prunus spinosa is considered by some authors the remote ancestor of the Domestica and Insititia plums, but as brought out in the discussion of the last named species, such parentage is very doubtful.

The Spinosa plum is a common and often pestiferous plant in its habitat, the roots forming such a mass that in general it is impossible for any other vegetation to grow in its vicinity. The plant is small, spreading and much branched and bristles with sharp thorns. The leaves are smaller than those of any of the other Old World species, ovate in shape and very finely serrate. The flowers are usually single but sometimes in pairs or threes and are borne in such number as to make a dazzling mass of white; comparatively few of these, however, set fruit. The fruit is round and small, usually less than half an inch in diameter, and, typically, so black as to have given rise to the old saying, “as black as a sloe.” The fruits are firm but rather juicy, with an acid, austere flavor, which makes them unfit for eating out of hand until frost-bitten, when the austereness is somewhat mitigated. The stone is much swollen, with one edge acute.

European nurserymen now and then offer trees of the Spinosa plum for fruit-growing, sometimes with the statement that the fruit is sweet. But pomologists do not speak highly of these cultivated Spinosas and hold that they are hardly worth cultivation. The wild plums are quite commonly picked for certain markets in Europe, however, especially those in which the Domesticas and Insititias are not common. With plenty of sugar the fruits make a very good conserve. In France the unripe fruit is pickled as a substitute for olives and the juice of the ripe fruit is sometimes used to make or adulterate cheap grades of port wine. In the country districts of Germany and Russia the fruit is crushed and fermented and spirit distilled from it.

The species is quite variable within limits, but since the wild fruits have been used from the time of the lake-dwellers of central Europe, without the appearance of desirable forms, the variations are not likely to give horticultural varieties worth cultivating for table use. The variations in the fruit are usually in color, the size and flavor changing but little. Several ornamental forms are in cultivation, of which the chief ones have been named.

4. PRUNUS CURDICA Fenzl and Fritsch.

The few herbarium specimens that the writer has seen of this species from southeastern Europe strongly resemble Prunus spinosa but Schneider in the above reference describing it from living specimens says that it differs from the species last named as follows: “Lower growth, about one-half as high, spreading squarrose ramification, much less thorniness; leaves more like domestica, when young hairy on both sides, later above nearly and underneath more or less glabrous; petiole shorter, not exceeding one cm.; blooms later, nearly with the leaves, white, about twenty-two mm. in diameter, borne almost always single in this species; pedicel finely pilose, in Prunus spinosa almost glabrous; stamens fewer, about twenty; fruit blue black, stem longer, exceeding twelve mm.”

So far as appears from the few and scant European references to the species it has no horticultural value.

5. PRUNUS COCOMILIA Tenore.

The writer has seen only herbarium specimens of this plant and has taken the description given from European texts. According to Schneider the species has been divided into two varieties by the Italian botanists. Prunus cocomilia typica having oblong-ovate fruit and Prunus cocomilia brutia having round fruit. Schneider holds also that Prunus pseudoarmeniaca Heldr. and Sart.[82] from Epirus and Thessaly is a variety of Prunus cocomilia differing chiefly in having more pointed leaves and smaller oblong-roundish red plums. The same author puts in this species still another plum, a hairy-leaved form from Thessaly which he calls Prunus cocomilia puberula. He places here also Prunus ursina Kotschy[83] which differs only in minor respects from the species, chiefly in having violet-red fruit though Boissier[84] mentions a yellow-fruited plum which he calls Prunus ursina flava. The last named plums come from Lebanon and North Syria.

6. PRUNUS CERASIFERA Ehrhart[85]

Prunus cerasifera, the Cherry plum, first came to notice in pomological literature as the Myrobalan plum, a name used as early as the last half of the Sixteenth Century by Tabernæ-Montanus and given prominence in the Rariorum Plantarum Historum, published by Clusius in 1601. Why applied to this plum is not known. Myrobalan had long before been used, and is still, as the name of several plum-like fruits of the East Indies, not of the genus Prunus, which are used in tanning, dyeing, ink-making and embalming. Until Ehrhart gave it the name Prunus cerasifera in 1789 it was known as the Myrobalan plum by botanists, some of whom, and nearly all horticulturists, have continued the use of the name until the present time.

Not a few of the botanists who have used Myrobalan for this plum have called it a botanical variety of Prunus domestica. Among these were Linnaeus and Seringe. Others, as Loisleur and Poiteau, have preferred the name for the species as distinguished by Ehrhart.

Many of the early botanists, as Tournefort in 1700, Ehrhart in 1701, Loudon in 1806 and Loisleur in 1812, gave the origin of the Cerasifera plums as North America, but upon what authority does not appear. On the other hand many European botanists, including Linnaeus, gave the habitat as Europe or Asia. The supposition that this plum came from North America hardly needs discussion. The plum flora of this continent has been well enough studied so that it can be said that no plant that could by any possibility be the Cerasifera plum grows on this side of the Atlantic. Neither does it seem logical to consider this an off-shoot of Prunus domestica, for fruit and tree-characters are distinctly different, and for a member of the genus Prunus are remarkably constant. Moreover, there is abundant evidence to show that this is a distinct species and that its nativity is in the Turkish and nearby countries in Europe and Asia and that there it has been in cultivation for a long time.

It is very significant that in the old herbals and botanies a frequent name of this fruit is “the Turkish plum.” But more specific and almost conclusive proof is that two forms of plums belonging to this species are known to come from the Caucasus region. Prunus divaricata[86] is now considered by some botanists to be a synonym of Prunus cerasifera and by others to be a botanical variety of the last named species. Ledebour, who named it, found it in the Trans-Caucasian region. It differs from the type only in having much divided, wide-spreading and nearly prostrate branches. The Pissardi plum, a purple-leaved form of this species, originated in Persia. A plum now growing in the Arnold Arboretum raised from seed from Turkestan, presumably from wild stock, is identical with plants of Cerasifera of European origin. And, according to Schneider,[87] this plum is known in the wild state in Caucasus, Trans-Caucasus, northern Persia and Turkestan.

The Cerasifera plums are small trees, usually upright but in some forms with spreading branches which are commonly unarmed, glabrous and brownish in color. The leaves are ovate and smaller and thinner and with more finely serrate margin than those of the Domestica plums. It blooms prolifically and bears large, white, single or paired flowers, making a most beautiful tree when in flower. The fruit is small, round, and cherry-like, from half an inch to an inch in diameter, usually red but sometimes yellow. The flesh is soft, sweetish or sub-acid and poor. The stone is turgid, smooth and pointed. The species is variable in nearly all tree-characters, and were it not surpassed by other plums for its fruit there would undoubtedly be a great number of varieties cultivated for the markets. There are, however, but few cultivated Cerasiferas, only nineteen being described in The Plums of New York. It is very generally distributed wherever plums are grown, because of the use to which it has been put as stocks for other species. For this purpose it is held in high esteem the world over. In the nurseries of New York it is now used more than any other stock and it is common to find it fruiting here and there from plants set for or used as stocks. In fact practically all the cultivated varieties have arisen as survivals of plants meant for stocks. It is almost certain that the Cerasifera, or Myrobalan, as it is universally known by horticulturists, dwarfs the cion and that it is not equally well suited to all varieties; but it does not “sprout” as badly as some other stocks, is adapted to many soils, and the young trees grow well and are rapidly budded, giving at the start a strong and vigorous orchard tree.

The Cerasifera plums are handsome trees. The foliage is a fresh and beautiful green and whether covered with a mass of flowers or loaded with red or yellow fruit these plums are as handsome as any of our cultivated fruit trees, and as desirable for ornamentals.

The hardiness, thriftiness, freedom from disease and adaptability to soils make the species desirable for hybridizing. A number of breeders of plums have made use of it with some indications of a promising future, several interesting hybrid offspring of this species being described in The Plums of New York.

The small number of varieties of Cerasifera cultivated for their fruit indicates that but little can be expected from this species by plum-growers, since so little has come from it in the shape of edible fruits, though it has been under general cultivation for over three hundred years, at least, as an ornamental and as a stock. Several valuable groups of ornamentals have arisen from Cerasifera, of which the following are most notable:—

In 1880 M. Pissard, gardener to the Shah of Persia, sent to France a purple-leaved plum which proved to be a form of Prunus cerasifera. To this plum Dippel[88] gave the name Prunus cerasifera atropurpurea, while horticulturists very generally call it Prunus pissardi. A close study of the purple-leaved plum reveals no character in which it differs from the species except in the color of foliage, flowers and fruit; the leaves are purple, as are also the calyx and peduncles of the flowers, while the fruit is a dark wine-red. These are but horticultural characters and do not seem to be of sufficient importance to establish for this plant a botanical variety. This view is strengthened by the fact that Jack[89] reports that seeds from the purple-leaved plum have produced plants which agree in all essential particulars with the species; while Kerr[90] has grown a purple-leaved plum from a variety of Prunus cerasifera.

Besides this well-known purple-leaved plum nurserymen offer Prunus pendula, a weeping form; Prunus planteriensis, bearing double white and red flowers; Prunus acutifolia, a plum with narrow, willow-like leaves; Prunus contorta, characterized by twisted, contorted foliage; Prunus elegans, Prunus gigantea, and a variety with yellow and another with variegated leaves, etc. All of these are probably horticultural varieties of Prunus cerasifera though some of them cannot be classified with surety.

Schneider[91] calls Prunus dasycarpa Ehrhart,[92] the Prunus armeniaca dasycarpa of Borkhausen,[93] a cross between Prunus cerasifera and Prunus armeniaca, one of the apricots.

7. PRUNUS MONTICOLA K. Koch

Prunus monticola is described by the above authors as a shrub-like plum from Asia Minor and Armenia having, so far as can be learned from European texts, little or no horticultural value. The herbarium specimens seen by the writer indicate that this species is closely related to Prunus cerasifera. The description of the species is abbreviated from Schneider.

8. PRUNUS TRIFLORA Roxburgh

A study of the botanical characters of the many Triflora plums under cultivation fails to show any lines of cleavage whereby the species can be divided. Of plums commonly grown in America it is not very closely related to any unless it be Prunus simonii. There are several plums from eastern and central Asia with which we are not at all familiar in America that may show relationship with Prunus triflora, chief of which are Prunus ichangana Schneider,[94] Prunus thibetica Franchet[95] and Prunus bokhariensis Royle,[96] the last a cultivated plum from northern India. These, in herbarium specimens, have some characters reminding one of Prunus triflora, others of Prunus domestica and still others, of Prunus cerasifera.

The Triflora, or Japanese,[97] plums are now cultivated in all parts of the world where plums are grown; yet outside of Japan and China they have been grown for their fruit less than half a century. Despite the fact that these plums have been grown in Asia for several centuries the wild form is not known. Indeed, there are doubts in the minds of some as to whether it constitutes a distinct species, Maximowicz, an authority on the flora of Japan, among others, holding that it is but a form of Prunus domestica. Roxburgh in naming it gave but little definite information in regard to the species, but the herbarium specimens of his in the Kew Herbarium are readily identified as identical with our Japanese plums.[98] The confusion between Prunus triflora and Prunus domestica seems needless, as the points of difference between these two species are several and very distinct and constant, the resemblances between Prunus triflora and some of the American species being much closer. So, too, the effort, sometimes made, to make more than one species out of Prunus triflora is straining a point, for though the types under cultivation vary considerably yet the variations are not greater than between varieties of other species of the genus Prunus.

Prunus triflora is almost certainly a native of China. According to Georgeson and Sargent, who have made extensive botanical explorations in the forests of Japan, there are no indigenous plum trees in that country. Dr. K. Miyake, botanist at the Agricultural College of the Imperial University, Tokyo, Japan, writes to this Station,[99] that Prunus triflora does not grow wild in Japan but was introduced there from China from two to four hundred years ago. Bretschneider[100] in his treatise on The Study and Value of Chinese Botanical Works says that the plum has been cultivated from ancient times in China and this indicates that the original habitat was in that country. Mr. F. N. Meyer, Agricultural Explorer for the United States Department of Agriculture, who has made extensive agricultural explorations in China, writes[101] that he has seen many trees of Prunus triflora cultivated in the Chekiang Province and also about Canton but that he had not found the species growing wild. Roxburgh says[102] that the shrub had been “received from China into our gardens in Bengal.” Forbes and Hemsley[103] state that varieties of this plum are cultivated in China and that it occurs in the wild state in the mountains near Peking as well as on the Tsunglin range in Shensi and Kansu. These writers are, however, uncertain as to where it is truly indigenous.

While the above and practically all evidence points to China as the original home of Prunus triflora it is likely that the habitat of the species cannot be accurately determined until western and southwestern China have been explored by botanists, these regions as yet being almost unknown to foreign scientists.

Notwithstanding the illustrious work of Kaempfer, Thunberg, Siebold and Fortune in sending to Europe the choicest plants of Japan and China, Prunus triflora seems to have reached the Old World through America at a very recent date. At least the species was not cultivated for its fruit in Europe until introduced from the United States as Japanese plums, and even yet they are but barely known in European orchards. The species was introduced into this country from Japan about 1870 by a Mr. Hough of Vacaville, California. According to Bailey,[104] who has given much attention to these plums, Mr. Hough obtained his trees from a Mr. Bridges, United States Consul to Japan. John Kelsey, Berkeley, California, produced the first ripe fruit of the Triflora plums in America in 1876 and 1877, and impressed by their value began recommending them. Owing to Mr. Kelsey’s efforts the propagation of these plums was begun on a large scale about 1883 by W. P. Hammon & Co., of Oakland, who commemorated Mr. Kelsey’s labors by naming the plum after him. The success of the Kelsey started the importation and origination of varieties and a veritable boom in Japanese plums was soon under way.

This fruit is a most valuable addition to our pomology, no less than ninety-two varieties now being under cultivation in America. At first it was thought desirable only for the southern states, but it proved to be nearly as hardy as the Domestica plums in the northern states and was soon widely distributed north and south. Beyond question it has suffered from over-praise, which has led to over-planting. As was of necessity the case, many untested and worthless varieties were offered fruit-growers, and these, with the failure of some of the extravagant claims for the really meritorious varieties, have given the Triflora plums a bad reputation with many fruit-growers. Now we have cultivated plums of this species for forty years and there has been time for the excitement of their discovery and the consequent reaction to abate making it possible to arrive more nearly at their true place in pomology.

The plums of this species possess several striking features that commend them to fruit-growers. Undoubtedly the most valuable attribute of the Triflora plums as cultivated fruits is their wide range of adaptability. All must admit that this group of varieties is less valuable than the Domestica varieties where both succeed, but the Triflora plums are adapted to a much wider range of country and of conditions than the Domesticas. But even where both types of plums succeed the newer plum introduces several very desirable features quite aside from additional variety which the many distinct sorts furnish. Thus, as a species, the Trifloras are more vigorous, productive, earlier in coming in bearing and more free from diseases, especially black-knot and leaf-blight, than the Domestica plums. The Trifloras are also less subject to curculio than most of the native and European species. They keep longer and ship as well as the better known Europeans. As compared with native varieties the plums from Japan are larger, handsomer and better flavored and keep and ship better. Some disadvantages are that they blossom so early as to be often caught by spring frosts; they are quite subject to brown-rot; for most part they are tenacious clingstones; the species, all in all, is less hardy to cold than the Domestica plums; lastly, they are inferior in quality to the varieties from Europe. The last fault is so serious that, though the average for the Triflora plums is high, making them unquestionably more desirable inhabitants of the orchard than any of the native species, they cannot compete with the Domesticas where the two types can be equally well grown.

The botanical differences between these Asiatic plums and those from Europe and America are most interesting. In 1859 Asa Gray called attention to the striking resemblances between the east coast floras of Asia and America. The Triflora plum is one of the plants which furnishes substantial evidence of this similarity and of the dissimilarity of the east and west coast floras of the two hemispheres. In general aspect the trees of the Triflora plums in summer or winter are much more like those of the American species than like those from Europe or West Asia; so, too, the fruits are more alike in appearance and in quality, and the peach-like foliage of the Trifloras might easily be mistaken for that of some of our varieties of Hortulana or Munsoniana. In the manner in which the buds are borne and in vernation the resemblance of the Oriental species to the Americanas, Hortulanas and Munsonianas is again most striking. In Asiatic and American species the buds are borne in twos and threes, while in the European species they are more often single or double.

The importance of this similarity of the Triflora plums to the most common American species is seen when Gray’s reason for the likenesses between the two floras is considered. This, briefly, is that similar types of post-glacial plants should persist in areas having like geographical positions and like climates; hence east-coast plants in one hemisphere should be expected to be similar to those of the east coast of the other hemisphere and the same with the west coast. Triflora plums are near of kin to American plums, then, because they have been evolved under similar conditions. This is a reason why these plums from Japan are adapted to so wide a range of country in America, and why, too, they are so free from the fungus troubles which attack European plums, but from which American plums suffer but little.

As might be expected from their nearness of kin the Triflora plums hybridize readily with the American species and especially with the Hortulanas and Munsonianas, the species they most resemble. Unfortunately an amalgamation of the Oriental plums with the Americanas is not so easily accomplished and that with the Domesticas is still more difficult. Hybrids with Prunus simonii are easily made and the progeny as a rule have much merit. Hybrids of the Trifloras with our native species give most promising results, a number of them being described in The Plums of New York. The fact that the Trifloras have been cultivated for several centuries, at least, means in their hybridization with American species that there is an amalgamation of domesticated characters with the similar but wilder characters of our native species.

It has been very difficult to establish a satisfactory nomenclature for the Triflora plums now grown in America. In spite of the excellent work of Berckmans,[105] Bailey[106] and Waugh,[107] in bringing order out of what was at one time utter confusion, there is still a great deal of uncertainty as to the identification of some varieties. The confusion began with the first extensive importation of these plums from Japan when names which the Japanese applied to classes or groups or the localities from which the plums came were made to apply in America to definite varieties. Many of the names under which the plums were imported have had to be dropped and the varieties boldly renamed. Another source of confusion has been that these, of all plums, seem most variable under changed conditions. Local environment in many instances in America changes somewhat the habit and appearance of varieties, making it difficult to decide whether two or more specimens of the same sort from different localities are identical varieties or distinct. Curiously enough, too, the trees of some varieties of plums seem to bear unlike fruit in different years, especially in the matter of time of ripening; that is, trees of some varieties do not always ripen their fruit in the same sequence, being earlier than another variety one year and possibly later the next. All fruits are more or less variable in this respect, but the Triflora plums are remarkably so, a fact that has added to the confusion in their nomenclature, since it adds to the difficulty of identifying varieties.

The cultivated varieties of Prunus triflora are also very diverse as regards tree-characters, especially as to vigor, hardiness and time of maturity of the fruit. The differences seem to be horticultural or those that come from cultivation, rather than botanical. Indeed, it seems impossible to place the numerous varieties in horticultural groups that are marked with any great degree of definiteness. A distinction of groups based on color is sometimes made, but the one character is insufficient to have classificatory value. In Japan, according to Georgeson, a division of the species is made with shape as the line of division. He says[108] “The round plums are designated by the term botankio, while those of an oval or pointed shape are called hattankio.” The varieties are sometimes loosely grouped into yellow and red-fleshed sorts. A serviceable classification would have to be founded on several or a considerable number of characters. Such a classification at present is impossible.

9. PRUNUS SIMONII Carrière