Indigenous to North America there are several species of Pyrus belong to the Malus or apple group. Sargent, in his Silva of North America, gives three species and one variety. These are P. rivularis Doug., found west of the Rocky Mountains from northern California to Alaska; P. angustifolia Ait., ranging from Pennsylvania to Tennessee and Florida; P. coronaria L., in the region from New York to Michigan, southward and westward to Missouri and Kansas; P. coronaria var. Iowensis, Wood, confined to the prairie states. In the American Garden, XII, 473, 1891, Professor Bailey raised var. Iowensis to specific rank, basing his decision upon fruit and leaf characteristics, and in the same article described the Soulard crab as a species. Later, however, he expressed it as his opinion that the latter is a hybrid, so according to the present classification, we have the four species, P. rivularis, P. angustifolia, P. coronaria, and P. Iowensis.
Proceedings of the Iowa Academy of Sciences
©1899 Iowa Academy of Science, Inc.
Craig, John and Hume, H. Harold
"Native Crab Apples and Their Cultivated Varieties,"
Proceedings of the Iowa Academy of Science, 7(1), 123-141.
Available at: https://scholarworks.uni.edu/pias/vol7/iss1/18