When Meriwether Lewis spent time at the residence of Pierre Chouteau in St. Louis in the early spring of 1804, he noted two trees which he had not observed before – the Osage Apple (later renamed the Osage Orange) and the Osage Plum.
Today, we know the Osage Orange as the Hedge Apple, but learning more about the Osage Plum isn’t easy. Most likely this plum was the native wild plum tree found throughout the area – the Prunus americana. The small, deciduous, single-trunk tree or multi-stemmed shrub enjoys growing in rocky or sandy soils in woodlands, near streams and meadows throughout Missouri.
Spring flowers are followed by edible, round, red plums (about 1” in diameter) which have a pale yellow pulp. While the fruit can be eaten raw, the small plums are best used in preserves and jellies. Meriwether collected cuttings of both trees which he sent back to Mr. Jefferson.
Source: Missouri Botanical Garden