The Collaborative International Dictionary of English v.0.48:

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.
      [1913 Webster]

   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.
         [1913 Webster]

   2. The merest trifle; a straw.
      [1913 Webster]

            John Bull's friendship is not worth a rush.
                                                  --Arbuthnot.
      [1913 Webster]

   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 (Zool.), 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 schoenanthus), used in Oriental medical
      practice.

   Wood rush, any plant of the genus Luzula, which differs
      in some technical characters from Juncus.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Andropogon \An`dro*po"gon\, n. [NL.; Gr. 'anh`r, 'andro`s, man +
   pw`gwn the beard.] (Bot.)
   A very large and important genus of grasses, found in nearly
   all parts of the world. It includes the lemon grass of Ceylon
   and the beard grass, or broom sedge, of the United States.
   The principal subgenus is Sorghum, including Andropogon
   sorghum and Andropogon halepensis, from which have been
   derived the Chinese sugar cane, the Johnson grass, the Aleppo
   grass, the broom corn, and the durra, or Indian millet.
   Several East Indian species, as Andropogon nardus and
   Andropogon sch[oe]nanthus, yield fragrant oils, used in
   perfumery.
   [Webster 1913 Suppl.]