According to that website, Poplar started out as a sickbay and supply office and was converted to the camp office when the officer-in-charge began residing full-time at the camp. An office for the commanding officer (CO) and executive officer (XO) was added to Poplar in 1970.
|Google Maps satellite view of Poplar cabin (center). Hickory Lodge is on the left.|
Sources: Camp David Tour; U.S. Navy; Google Maps