The community ecology of a 0.49 ha wetland was studied at a site that was highly disrupted by past limestone mining. The wetland occurs in a potentially stressful environment for many plants because only a thin layer of soil covers bedrock and moisture fluctuations range from inundation to desiccation. In the wetland, 86.4% of the species are native (including the 11 most frequent species). Variation in species frequency across the wetland is controlled by soil depth and soil moisture. Of the native species occurring in the wetland, 80% also occur in two nearby nature preserves; some of these species are associated with ruderal habitats.