Incoming and outgoing correspondence between George Engelmann and Charles Christopher Parry, for 1851-1884. The correspondence relates to botany, botanical surveys and expeditions sponsored by the Smithsonian Institution and other U.S. government agencies. Letters discuss the Emory expedition in New Mexico, and Parry's travels and collection trips to the American West and Southwest. Also included are descriptions of various plants, including many Cactaceae and Pinus species.

Folders contain original letters and postcards, as well as photocopies and abstracts of the original material.