Source : Webster's Revised Unabridged Dictionary (1913)

Rush \Rush\, n. [OE. rusche, rische, resche, AS. risce, akin to
   LG. rusk, risch, D. & G. rusch; all probably fr. L. ruscum
   butcher's broom; akin to Goth. raus reed, G. rohr.]
   1. (Bot.) A name given to many aquatic or marsh-growing
      endogenous plants with soft, slender stems, as the species
      of {Juncus} and {Scirpus}.

   Note: Some species are used in bottoming chairs and plaiting
         mats, and the pith is used in some places for wicks to
         lamps and rushlights.

   2. The merest trifle; a straw.

            John Bull's friendship is not worth a rush.
                                                  --Arbuthnot.

   {Bog rush}. See under {Bog}.

   {Club rush}, any rush of the genus {Scirpus}.

   {Flowering rush}. See under {Flowering}.

   {Nut rush}
      (a) Any plant of the genus {Scleria}, rushlike plants with
          hard nutlike fruits.
      (b) A name for several species of {Cyperus} having
          tuberous roots.

   {Rush broom}, an Australian leguminous plant ({Viminaria
      denudata}), having long, slender branches. Also, the
      Spanish broom. See under {Spanish}.

   {Rush candle}, See under {Candle}.

   {Rush grass}, any grass of the genus {Vilfa}, grasses with
      wiry stems and one-flowered spikelets.

   {Rush toad} (Zo["o]l.), the natterjack.

   {Scouring rush}. (Bot.) Same as {Dutch rush}, under {Dutch.}
      

   {Spike rush}, any rushlike plant of the genus {Eleocharis},
      in which the flowers grow in dense spikes.

   {Sweet rush}, a sweet-scented grass of Arabia, etc.
      ({Andropogon sch[oe]nanthus}), used in Oriental medical
      practice.

   {Wood rush}, any plant of the genus {Luzula}, which differs
      in some technical characters from {Juncus}.

Spike \Spike\, n. [Akin to LG. spiker, spieker, a large nail, D.
   spijker, Sw. spik, Dan. spiger, Icel. sp[=i]k; all perhaps
   from L. spica a point, an ear of grain; but in the sense of
   nail more likely akin to E. spoke of a wheel. Cf. {Spine}.]
   1. A sort of very large nail; also, a piece of pointed iron
      set with points upward or outward.

   2. Anything resembling such a nail in shape.

            He wears on his head the corona radiata . . .; the
            spikes that shoot out represent the rays of the sun.
                                                  --Addison.

   3. An ear of corn or grain.

   4. (Bot.) A kind of flower cluster in which sessile flowers
      are arranged on an unbranched elongated axis.

   {Spike grass} (Bot.), either of two tall perennial American
      grasses ({Uniola paniculata}, and {U. latifolia}) having
      broad leaves and large flattened spikelets.

   {Spike rush}. (Bot.) See under {Rush}.

   {Spike shell} (Zo["o]l.), any pteropod of the genus
      {Styliola} having a slender conical shell.

   {Spike team}, three horses, or a horse and a yoke of oxen,
      harnessed together, a horse leading the oxen or the span.
      [U.S.]

Source : WordNet®

spike rush
     n : a sedge of the genus Eleocharis