Source : Webster's Revised Unabridged Dictionary (1913)

   {Ground rattlesnake} (Zo["o]l.), a small rattlesnake
      ({Caudisona, or Sistrurus, miliaria}) of the Southern
      United States, having a small rattle. It has nine large
      scales on its head.

   {Rattlesnake fern} (Bot.), a common American fern
      ({Botrychium Virginianum}) having a triangular decompound
      frond and a long-stalked panicle of spore cases rising
      from the middle of the frond.

   {Rattlesnake grass} (Bot.), a handsome American grass
      ({Glyceria Canadensis}) with an ample panicle of rather
      large ovate spikelets, each one composed of imbricated
      parts and slightly resembling the rattle of the
      rattlesnake. Sometimes called {quaking grass}.

   {Rattlesnake plantain} (Bot.), See under {Plantain}.

   {Rattlesnake root} (Bot.), a name given to certain American
      species of the composite genus {Prenanthes} ({P. alba} and
      {P. serpentaria}), formerly asserted to cure the bite of
      the rattlesnake. Calling also {lion's foot}, {gall of the
      earth}, and {white lettuce}.

   {Rattlesnake's master} (Bot.)
   (a) A species of Agave ({Agave Virginica}) growing in the
       Southern United States.
   (b) An umbelliferous plant ({Eryngium yucc[ae]folium}) with
       large bristly-fringed linear leaves.
   (c) A composite plant, the blazing star ({Liatris
       squarrosa}).

   {Rattlesnake weed} (Bot.), a plant of the composite genus
      {Hieracium} ({H. venosum}); -- probably so named from its
      spotted leaves. See also {Snakeroot}.

Source : WordNet®

rattlesnake's master
     n : coarse prickly perennial eryngo of United States thought to
         cure rattlesnake bite [syn: {rattlesnake master}, {button
         snakeroot}, {Eryngium yuccifolium}]