Plants annual, papillate with crystalline globules occasional, glabrous. Stems prostrate, branched, 1-4 dm. Leaves: petiole clasping, broadly scarious-winged at base; blade oblanceolate to spatulate, 3-5 cm, widest distally, base tapered. Inflorescences: flowers solitary; pedicel absent. Flowers: calyx lobes triangular-ovate, with small apical appendages, 3.5 mm; stamens 5; filaments 1 mm; pistil 2-carpellate; ovary 2-loculed; styles 2. Capsules ovoid-ellipsoid, 4.5 mm. Seeds 10, brown, 1.5 mm, rugose with granular ridges.

Flowering summer (Jun-Aug). Wet depressions in coastal sand dunes; 0-4 m; Tex.

Apparently Sesuvium trianthemoides is known only from the type locality. Additional investigation may reveal this entity should be included in S. maritimum.