Place
- Olympic Peninsula, along beach, Queets1
- Olympic Peninsula, west of Ozette Lake1
- Ontonagon1
- Orono1
- Ottawa1
- Ottawa National Forest NW near Bessemer1
- Ottawa National Forest, wetland survey, trans. 307A, plot 21
- Pacific1
- Papua New Guinea1
- Pawlet1
- Pender1
- Penobscot1
- Pictured Rocks, Miners Castle1
- Pigeon Point1
- Pinckney, near1
- Piscataquis1
- Piscataquis River Valley1
- Porcupine Mountains1
- Potter1
- Powell1