This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
A small tree, sometimes 25o high, the trunk 7' in diameter, the branches somewhat thorny. Leaves lanceolate or oblong-lanceolate, acute at the apex, serrulate, often rounded at the base, glabrous when mature, 3-5' long; flowers smaller than those of the preceding species, in lateral umbels, expanding before the leaves; drupe red, globose, 6"-9" in diameter, nearly destitute of bloom, thin-skinned, its stone ovoid, hardly flattened, both edges rounded, one of them slightly grooved.
P. alleghaniensis Porter, Bot. Gaz. 2: 85. 1877.
A low, straggling shrub or small tree, with maximum height of about 15o and trunk diameter of 5', seldom thorny. Leaves ovate-oblong or obovate, acute or acuminate, finely and sharply serrate, rounded at the base, pubescent when young, glabrous or very nearly so when old; flowers similar to those of P. americana, about 7" broad; drupe globose-ovoid, about 5" in greatest diameter, very dark purple with a conspicuous bloom; pulp pleasantly acid; stone slightly flattened, a shallow groove on one margin, a slight expansion on the other.
Prunus maritima Wang. Am. 103. 1781.
Prunus sphaerocarpa Michx. Fl. Bor. Am. 1: 284. 1803.
A low much-branched shrub, 1°-7° high, not thorny. Leaves oval, ovate or obovate, finely and sharply serrate, acutish or acute at the apex, rounded at the base, pubescent beneath even when old; flowers white, numerous, showy, in sessile lateral umbels, expanding before the leaves, 5"-8" broad; petals obovate; drupe globose, purple, 1/2'-1' in diameter, sweet when ripe, covered with a bloom; stone little flattened, acute on one margin, slightly grooved on the other, usually pointed at both ends.
On seabeaches and in sandy soil near the coast, Virginia to New Brunswick. April-May. Fruit ripe in Sept. or Oct.