Thirty-four shallow, seasonally flooded ponds associated with sandstone strata overlying limestone strata, have been floristically surveyed in the Ridge and Valley physiographic region of Maryland and West Virginia. Most ponds are typically wet in winter and spring, but dry in summer and early autumn. The ponds are small, muck-bottomed, and usually have less than 50 cm standing water when inundated. Vegetation varies from sparse to aspect-dominated by sedges, grasses, or woody plants. Fifty-seven vascular plant species are reported from these ponds, including several that are considered rare in the two states. The endangered sedge Scirpus ancistrochaetus is reported for the first time from both states. Sizes for the clonal populations of this sedge vary among sites from several hundred to several thousand stems.