Oenothera primiveris, Evening Primrose Family, Herbarium specimen from Mexican Boundary Survey

While marking the U.S.-Mexico boundary, Army surveyors also studied the flora and fauna of the borderland. They published a three-volume illustrated report and collected plant and animal specimens—among them, this desert evening primrose. This flower is native to the southwestern United States and northern Mexico and well adapted to the arid climate.

Smithsonian Institution, National Museum of Natural History