Species: Carex multicostata

Many-ribbed Sedge is a perennial, grass-like plant that forms small to large clumps with stems reaching up to 6 dm high that have basal leaves which are reduced to scales. The flat leaves are 2-4 mm wide and crowded just above those that are reduced. Flowers are clustered in egg-shaped spikes, 6-10 mm long; the female flowers (perigynia) occupy most of the spike, but there are a few inconspicuous male flowers at the base. Spikes are aggregated into a head at the top of the stem and subtended by 2-3 inconspicuous bracts. Scales subtending each perigynia are membranous and brownish with a thickened midrib and slightly shorter and narrower than the perigynia. Green to brownish perigynia are lance-shaped and 4-6 mm long with a gently tapered tip that is entire-margined, deeply cleft, and round in cross-section at the tip. There are 10 or more nerves on the convex outer face of the perigynia. There are 2 stigmas, and the seed is flattened.