Plants small and weak-stemmed, flaccid and ± plumose when submerged to (more frequently) sprawling in thin mats; capitulum ± compact and with a strong terminal bud; pale green to greenish white. Stem pale green; superficial cortex of 1--2 layers of thin-walled and well differentiated cells. Stem leaves large, ovate to oblong-ovate, ca 2 mm, more or less spreading; apex rounded and serrulate; hyaline cells fibrillose and often 1--septate, convex surface generally aporose, concave surface with 1--several round pores per cell in ends and angles. Branches unranked to slightly 5-ranked, often short and blunt at distal end. Branch fascicles with 1--2 spreading and 0--1 pendent branches. Branch stems green, with cortex enlarged with conspicuous retort cells. Branch leaves ovate to oblong-quadrate, 1.2--2.5 mm, not undulate or recurved when dry, strongly toothed across apex and serrulate on margins; hyaline cells with to 4 small round ringed pores at cell ends on convex surface, small round wall thinnings in the cell ends and angles on the concave surface; chlorophyllous cells trapezoidal in transverse section, more broadly exposed on the convex surface. Sexual condition monoicous. Spores 38--48 µm; both surfaces covered with fine to moderately coarse papillae; proximal laesura less than 0.4 spore radius.

On the coastal plain, commonly in prostrate mats on damp sand, often in recently burned or cleared areas, also occasionally floating in ditches; Ala., Fla., Ga., La., Miss., N.C., S.C., Va.

Sporophytes are common, being immersed or exserted. The wide truncate branch leaves easily distinguish S. fitzgeraldii in most situations. Floating plants are not as quickly identified$ but can be told from other similar species of sect. Cuspidata because the branch leaves are still wider and more than those of similar species.