Herbs, annual, procumbent to erect, dark green, 2-7 dm. Stems ascending or erect, light brownish green, 1-several-branched mainly in distal part of plant, becoming woody at base; branches ascending or erect. Leaves ascending; blade linear, 17-30 × 0.7-1.5 mm, widest proximal to middle, apex acute. Glomes on main stem and lateral branches, not crowded into compound spikes, 1-3-flowered; bracts shorter than leaves, 4-12 mm. Flowers bisexual; perianth ± zygomorphic or irregular (segments slightly unequal), 2-4 mm diam.; perianth segments abaxially rounded and keeled, distally hooded, apex acute; stigmas 2-3. Seeds dimorphic; lenticular, 1.5-2.3 mm diam., with seed coat black to reddish, finely reticulate; or flat, 1.5-2.3 mm diam., with seed coat brown, dull. 2n = 90. Flowering late summer-fall. Tidal flats, salt marshes; 1-10 m; of conservation concern; N.B., N.S., Que.; N.J., N.Y. Besides being confirmed in the range given above, this rare species is said to occur along the coast from New Hampshire to Canada (S. E. Clemants 1992).