Culms arcuate or slightly sinuous, 10-35 cm. Leaves of flowering stems shorter than to equaling culms, 1.4-4.6 mm wide, ligules of distal cauline leaves usually obsolete. Inflorescences: peduncles of terminal staminate spikes (1-)3-28 mm; proximal pistillate spikes (1-)2-5, approximate, the proximal usually distant and pedunculate, elliptic, 5.3-8.5 mm wide; terminal staminate spikes pedunculate, 9-23.8 × 1.3-3.3 mm. Perigynia dark olive to green, (2.7-)3.2-3.8(-4.2) × 1.1-1.7 mm wide, apex gradually contracted into a smooth or slightly scabrous, straight or slightly curved (less than 28°) beak; beak 0.7-1.7 mm. Achenes 1.1-1.5 × 0.9-1.2 mm.

Fruiting Jul-Aug. Moist, open, acidic coastal flats, meadows, not found on lime-rich soils; 0-200 m; introduced; Nfld. and Labr., N.S., Que.; Conn., N.J.; Europe (from Norway and Finland to Portugal, Italy, and Hungary); Africa (Morocco); Atlantic Islands (Azores, Madeira).

The distribution of Carex viridula subsp. oedocarpa in North America coincides with areas of early European settlement in maritime Canada and northeastern United States. This taxon occurs in natural coastal grasslands in Europe and probably is introduced in North America, where it persists in coastal meadows that were managed as hay fields for colonists´ livestock.