_Culm_ two to three feet high, with a very solid exterior, but _spongy_ within, compressed, and deeply grooved on its inner angle the whole length between the joints. _Leaves_ long, narrow, and acute, scabrous on the margin and midrib. _Sheaths_ compressed, corresponding with the culm, shorter than the internodes, open, with membraneous margins. _Peduncles_ short, clothed with a thin membraneous acute pointed sheath, which generally encloses also the base of the spike. _Spikes_ two to three inches long. The flowers are arranged in alternate order, but occupy only one side of the rachis, as in the _R. dimidiata_. The neutral florets, or _clavate_ pedicels, are joined _laterally_ to the perfect flowers. Articulations of the rachis remarkably tumid, attenuated beneath, flat on the interior side, exteriorly convex, scabrous, and longitudinally striate. The exterior valve of the calyx, in the perfect flowers, is ovate, obtuse, very thick, cartilaginous, the inner margin inflected, and deeply marked on its outer surface with from three to five _corrugations_, with longitudinal ridges between them; the interior valve is smaller, of equal length, acute, ruled, coriaceous, smooth, and with the inner margin also inflected. The valves of the corolla are membraneous, ovate, acute, white, shorter than the calyx, the exterior one the longest. The neutral florets are sometimes male, but most commonly consist of nothing more than a 2-valved calyx, the valves equal, gaping, scabrous, and much smaller than those of the perfect flower. _Stamens_ 3, very short. _Anthers_ twin, yellow. _Styles_ 2, rather longer than the stamens. _Stigmas_ small, plumose, dark purple. _Discovered_ between St. Mary's and Jefferson, in Camden county, Georgia, on the 13th of July, 1813. _Inhabits_ flat, moist pine barren. I have not seen it "on the sea-coast of Florida." OBSERVATIONS.