Prunus americana mollis is a western and southwestern form of Prunus americana, the sub-species being distinguished from the species by the amount and character of the pubescence on the leaves and shoots. The leaves, petioles and shoots of this plum are soft-pubescent, almost tomentose, the tomentum being pale in color and usually very dense; the calyx-lobes are pubescent on both sides and the pedicels are appressed and densely pubescent. According to Bailey, there is a form of this sub-species “with flowers as completely double as those of St. Peter’s wreath, or similar spireas.” This double-flowering plum we have not seen.
It is impossible to give the range of Prunus americana mollis as the woolly-leaved plum of the west gradually passes into the smooth-leaved species of the east and the two forms are not infrequently mixed in the South and Southwest; or possibly it would be better to say that they run into each other though the extreme forms are sufficiently distinct as to be readily mistaken for separate species. It can only be said that it is to be found in the greatest abundance in the region extending from southern Iowa through Missouri. Only two varieties of this plum, Wolf and Van Buren, are in general cultivation, both of which originated in Iowa. In neither fruit nor tree-characters do these differ greatly from the Americana plums.
A plum with pubescent leaves belonging to the Americana series known locally as the Big Tree plum, occurs from western Tennessee, south-westward through the extreme southern portion of Missouri, through Arkansas, southern Oklahoma, extending westward in central Texas, at least, as far as the Colorado River and reaching its southwestern limit in northern Mexico. From specimens of this plum in several herbaria and from studies made of it in the field by W. F. Wight of the United States Department of Agriculture, it would seem that this plum is a distinct species, its chief distinguishing character being the great size attained by the tree. So far as it is known the Big Tree has no cultivated forms unless it be Bilona, supposed to be a hybrid between this species and Prunus triflora, now growing on the grounds of F. T. Ramsey, Austin, Texas.
11. PRUNUS HORTULANA Bailey[116]
PRUNUS HORTULANA
1. Bailey Gar. and For. 5:90. 1892. 2. Sargent Sil. N. Am. 4:23, Pl. 151. 1892. 3. Waugh Vt. Sta. An. Rpt. 10:99-105. 1897. 4. Mohr Torrey Bot. Club Bul. 26:118. 1899. 5. Bailey Cyc. Am. Hort. 1450, fig. 1901. 6. Mohr Cont. U. S. Nat. Herb. 6:551. 1901.
P. americana, var.? 7. Patterson List Pl. Oquawka 5. 1874.
Tree attaining a height of thirty feet or more, vigorous in growth; trunk sometimes a foot in diameter; trunk and branches rough and shaggy becoming furrowed in age; bark gray-brown, thick and containing deposits of red cork cells which show as bright red blotches or as thick layers when the bark is sectioned, these deposits, especially in quantity, characterizing the species; branches very spreading and open, twiggy, slender, thorny; branchlets light green at first, becoming reddish-brown, glabrous and glossy; lenticels few, large, very coarse, raised, characteristic of the species.
Winter-buds plump, very small, obtuse, appressed; leaves one and three-quarters inches wide to five inches in length, long-oval with a tapering, pointed, acuminate apex, peach-like, base abrupt, texture thin, becoming leathery, margins serrate, almost crenate, sometimes in a double series, glandular; upper surface smooth, glossy, glabrous; lower surface light green, almost glabrous except on ribs and veins which are very pubescent, with characteristic orange color, midrib grooved above, rounded below, very prominent; petioles slender, an inch in length, pubescent on the upper side, tinged with red; glands two to eight, small, globose, mostly on the petioles.