Source : Webster's Revised Unabridged Dictionary (1913)

Sedge \Sedge\, n. [OE. segge, AS. secg; akin to LG. segge; --
   probably named from its bladelike appearance, and akin to L.
   secare to cut, E. saw a cutting instrument; cf. Ir. seisg, W.
   hesg. Cf. {Hassock}, {Saw} the instrument.]
   1. (Bot.) Any plant of the genus {Carex}, perennial,
      endogenous herbs, often growing in dense tufts in marshy
      places. They have triangular jointless stems, a spiked
      inflorescence, and long grasslike leaves which are usually
      rough on the margins and midrib. There are several hundred
      species.

   Note: The name is sometimes given to any other plant of the
         order {Cyperace[ae]}, which includes {Carex},
         {Cyperus}, {Scirpus}, and many other genera of rushlike
         plants.

   2. (Zo["o]l.) A flock of herons.

   {Sedge ken} (Zo["o]l.), the clapper rail. See under 5th
      {Rail}.

   {Sedge warbler} (Zo["o]l.), a small European singing bird
      ({Acrocephalus phragmitis}). It often builds its nest
      among reeds; -- called also {sedge bird}, {sedge wren},
      {night warbler}, and {Scotch nightingale}.

Source : WordNet®

sedge
     n : grasslike or rushlike plant growing in wet places having
         solid stems, narrow grasslike leaves and spikelets of
         inconspicuous flowers