Captain John Donnell Smith of Baltimore, Maryland was a biologist and taxonomist. He was also an officer in the Confederate army.
He was a graduate of Yale in 1847, where he was a member of Skull and Bones.
In January 1906, he presented his herbarium consisting of more than 100,000 mounted specimens and his botanical library of over 1600 bound volumes to the Smithsonian Institution. The books pertain mostly to the systematic botany of Mexico and Central America and remain in Baltimore. The herbarium now forms part of the U.S. National Herbarium reference.
He was a botanical researcher; a trustee of Peabody Institute in Baltimore. He was a Captain in the Confederate Army, and Commander of Battery A, 10th Battalion of Virginia Artillery, serving in every campaign and battle of the Army of Northern Virginia. He was severely wounded at Gettysburg, and was present at the surrender at Appomattox in April 1865.
He died at age 99. In his last years he was celebrated as the oldest living graduate of Yale.