- Pearre Road, in woods north of the school bus turn around.1
- Pilot serpentine barren.1
- Piney Branch Bog, 1.3 km NNE of Brice, 1.8 km SSE of Piney Church & 8.35 km NE of LaPlata.1
- Piscataway Park, National Colonial Farm, pond edge near parking area near main office.1
- Piscataway Park, near western entrance to Accokeek Creek boardwalk.1
- Poplar Lick Trail near Big Run Park.1
- Route 177 about 7 miles NW of Gibson Island. "Fresh Pond".1
- Saint Mary's1
- Sandy Point State Park.1
- Sideling Hill Creek at Ziegler Road.1
- Skinners Run at River Road & Mount Zion Road.1
- Smithville Lake, Possum Hill Road & Noble Road, along banks of creek south of the lake.1
- Smithville Lake, Possum Hill Road & Noble Road, south of the lake.1
- Soldiers Delight serpentine area, on north side of Sherwood Road 50-250 m from Deer Park Road.1
- Somerset1
- South of Frederick, along the Monocacy River, at MD Rt 355, Urbana Pike.1
- South side of Maryland Route 374 (Libertytown Road), 1.8 mi west of Ninepin Branch Road, on west floodplain of Pocomoke River.1
- St. Mary's1
- Suitland Bog north of the junction of Suitland Parkway & Suitland Road.1
- Town of Annapolis Junction, Little Patuxent Oxbow Lake, near Brock Bridge Road & the Little Patuxent River.1