Rhynchospora inundata is largely confined to lower Coastal Plain terraces, mostly along the present coast. Typical plants have narrow fruit bodies and narrow inflorescences of sparse clusters, well overtopped by leaves and erect leafy bracts. By contrast, plants of R. careyana have broader fruits, shorter perianths, and larger, broader inflorescences that overtop most or all leaves and bracts. In general, plants of R. careyana are more robust and grow in more acid sites than those of R. inundata. Southward in the Atlantic Coastal and Gulf Coastal plains are broad areas of ecotone where the two species intergrade.