Source : Webster's Revised Unabridged Dictionary (1913)

Reed \Reed\, n. [AS. hre['o]d; akin to D. riet, G. riet, ried,
   OHG. kriot, riot.]
   1. (Bot.) A name given to many tall and coarse grasses or
      grasslike plants, and their slender, often jointed, stems,
      such as the various kinds of bamboo, and especially the
      common reed of Europe and North America ({Phragmites
      communis}).

   2. A musical instrument made of the hollow joint of some
      plant; a rustic or pastoral pipe.

            Arcadian pipe, the pastoral reed Of Hermes.
                                                  --Milton.

   3. An arrow, as made of a reed. --Prior.

   4. Straw prepared for thatching a roof. [Prov. Eng.]

   5. (Mus.)
      (a) A small piece of cane or wood attached to the
          mouthpiece of certain instruments, and set in
          vibration by the breath. In the clarinet it is a
          single fiat reed; in the oboe and bassoon it is
          double, forming a compressed tube.
      (b) One of the thin pieces of metal, the vibration of
          which produce the tones of a melodeon, accordeon,
          harmonium, or seraphine; also attached to certain sets
          or registers of pipes in an organ.

   6. (Weaving) A frame having parallel flat stripe of metal or
      reed, between which the warp threads pass, set in the
      swinging lathe or batten of a loom for beating up the
      weft; a sley. See {Batten}.

   7. (Mining) A tube containing the train of powder for
      igniting the charge in blasting.

   8. (Arch.) Same as {Reeding}.

   {Egyptian reed} (Bot.), the papyrus.

   {Free reed} (Mus.), a reed whose edges do not overlap the
      wind passage, -- used in the harmonium, concertina, etc.
      It is distinguished from the beating or striking reed of
      the organ and clarinet.

   {Meadow reed grass} (Bot.), the {Glyceria aquatica}, a tall
      grass found in wet places.

   {Reed babbler}. See {Reedbird}.

   {Reed bunting} (Zo["o]l.) A European sparrow ({Emberiza
      sch[oe]niclus}) which frequents marshy places; -- called
      also {reed sparrow}, {ring bunting}.
      (b) Reedling.

   {Reed canary grass} (Bot.), a tall wild grass ({Phalaris
      arundinacea}).

   {Reed grass}. (Bot.)
      (a) The common reed. See {Reed}, 1.
      (b) A plant of the genus {Sparganium}; bur reed. See under
          {Bur}.

   {Reed organ} (Mus.), an organ in which the wind acts on a set
      of free reeds, as the harmonium, melodeon, concertina,
      etc.

   {Reed pipe} (Mus.), a pipe of an organ furnished with a reed.
      

   {Reed sparrow}. (Zo["o]l.) See {Reed bunting}, above.

   {Reed stop} (Mus.), a set of pipes in an organ furnished with
      reeds.

   {Reed warbler}. (Zo["o]l.)
      (a) A small European warbler ({Acrocephalus streperus});
          -- called also {reed wren}.
      (b) Any one of several species of Indian and Australian
          warblers of the genera {Acrocephalus}, {Calamoherpe},
          and {Arundinax}. They are excellent singers.

   {Sea-sand reed} (Bot.), a kind of coarse grass ({Ammophila
      arundinacea}). See {Beach grass}, under {Beach}.

   {Wood reed grass} (Bot.), a tall, elegant grass ({Cinna
      arundinacea}), common in moist woods.

Source : WordNet®

reed grass
     n : any of various tall perennial grasses of the genus
         Calamagrostis having feathery plumes; natives of
         marshland fens and wet woodlands of temperate northern
         hemisphere