[3] He travelled to South America and became a medical doctor, serving with the Union Army during the American Civil War.

"He collected specimens in the southwestern United States, Florida, Mexico (including Baja California), and South America.

[7][8] Palmer wrote an 1871 report, Food Products of the North American Indians,[9] which was one of the pioneering works in ethnobotany.

While most of Palmer's archaeological research was performed in Arkansas, he also excavated mounds in Alabama, Louisiana, Mississippi, Tennessee, and Georgia.

[12][13] Palmer's Baja California collections recovered from a site near Bahía de los Ángeles was subsequently described and analysed by William C. Massey and Carolyn M.

[14][15] After the Mound Exploration project was completed, Palmer returned to botany and natural history and worked as a Smithsonian field representative,[6] a scientist at the Smithsonian's Bureau of American Ethnology, and a collector and expert at the United States Department of Agriculture in Washington, D.C., until his death on 10 April 1911.