In the region where it is found wild the Maritima plum is a rather common article of trade. The fruit is usually sold by the quart, the price being five or ten cents, and is used for both dessert and culinary purposes though for most part for the latter.
The species is one of the most variable of the true plums and there is, probably must ever be, much disagreement as to its botanical relationships. Several botanical varieties of Prunus maritima have already been named and there are yet groups within the species which seem to be nearly as distinct as those described and possibly worth distinguishing. Since the variations show in the size, color and edible qualities of the fruit, as well as in the characters of the plant, it is to be expected that the species has a horticultural future though at present it has but one cultivated variety—Bassett. Professor J. W. Macfarlane of the University of Pennsylvania has shown well the great range of variations in this plum both from botanical and horticultural aspects.[142] He holds that these variations are sufficiently distinct to make many varieties of this plum in the wild, to which DeVries agrees with the statement that they indicate “the existence of separate races as elementary species.”[143] The plum which Small has described as Prunus gravesii, to be discussed later, is a marked variation of Prunus maritima.
As it grows on the sea-coast Prunus maritima is a low bush three to six feet high, occasionally reaching a height of ten or twelve feet. Usually the plant is straggling but sometimes it is compact or even tree-like. Inland, on better soils, or under cultivation it makes a rather handsome dwarf tree. The flowers are borne in great numbers, completely covering the plant and coming later than most of the plums bloom. The species bears fruit very abundantly, which is always attractive but of quite diverse value for food. The fruit varies in size from a half to three-quarters of an inch in diameter and is almost spherical, though sometimes oval and with or without a distinct suture. The usual color is a rich bluish-black with a waxy bloom, but red, yellow, amber and orange fruits are often found. In taste the Maritima plums range from inedible to nearly as rich a flavor as is found in the best of the Domestica plums. Besides variations in the above and other qualities, Macfarlane calls attention to the range in ripening of the fruit of this plum, showing that it extends over a period of two months, an exceptionally wide variation for a wild plant.
This plum has a number of qualities that commend it to the fruit-grower. Since in the wild it grows on sandy soils it is not likely under cultivation to make great demands on either the moisture or the fertility of soils. It is very hardy and very productive and seldom fails to bear. It seems to be free or nearly so from some of the pests of cultivated plums. Lastly, the great number of wild varieties of the plums give many starting points from which to breed cultivated varieties. Two objections to the wild fruits are that when the fruit is harvested the juice often exudes from the wound made by the parting from the stem, and secondly, the secretion of some substance forming a dark colored, hard core in the pulp which gives a very bitter taste to the fruit. The last defect is very common in the wild plums and is probably due to the sting of an insect. Under cultivation it may be possible to obtain fruits free from these faults.
It would be desirable if some of the characters enumerated above could be combined with those of other species. Burbank has hybridized the Maritima plum with other species, with promising results. Of these he writes under date of December 6, 1909, as follows:
“I first began raising Prunus maritima about 1887—twenty-two years ago—collecting myself and having specimens sent me all the way from the coast of Labrador to South Carolina, the finest of which were obtained from the eastern coast of Massachusetts. Among the seedlings, of which I raised and fruited several hundred thousands, were yellow, red, purple and almost black ones, early and late, round, oval, oblate and flattened, with big stones and little stones, free stone and cling stone, and much variety in productiveness and growth of the young bushes, but not one of them the first two or three generations were very much increased in size—probably the largest being about the size of a cranberry or a small hazelnut—and none of them of very exceptional quality, though their habit of blooming late was a tremendous advantage, as they invariably escaped our spring frosts. This, with their unusual hardiness induced me to continue experimenting with them. Finally after some ten years I obtained a very delicious variety, about an inch in length and three-quarters of an inch in diameter, tree much increased in size, larger foliage and more productive and producing enormous quantities of most delicious fruit. From this I raised a great many thousand, almost as good and a few of them even better, several hundred of which have been selected and are now bearing on my Sebastopol place. Some of these improved seedling trees grow five to ten times as large as the ordinary Maritima, with larger leaves and in every possible way improved. My greatest success with this species (and one of the most striking occurrences in my work with plums) was produced by pollinating one of the somewhat improved Maritimas with Prunus triflora.
“The very first generation, a plum was produced which is an astonishing grower for a Maritima—almost equal to the Triflora, with large, broad glossy foliage of almost the exact shape of the Maritima, Maritima blossoms, and fruit weighing nearly one-quarter of a pound each, with an improved superior Maritima flavor, Maritima pit in form, but enlarged. The most singular peculiarity of this plum, which is so enormous, is that the trees commence to bloom about with the Triflora and bloom and bear fruit all summer, so that blossoms, young fruit and the enormous deep red ripening fruit can be seen on the trees at the same time.”
21. PRUNUS GRAVESII Small
1. Small Torrey Bot. Club Bul. 24:44, Pl. 292. 1897. 2. Britton and Brown N. Am. Trees 2:249. 1897. 3. Robinson and Fernald Gray’s Man. Ed. 7:498. 1908.