[W/K] :: horsetails

  Equisetum \Eq`ui*se"tum\, n.; pl. Equiseta. [L., the
     horsetail, fr. equus horse + seta a thick,, stiff hair,
     bristle.] (Bot.)
     A genus of vascular, cryptogamic, herbaceous plants; -- also
     called horsetails.
     [1913 Webster]
  
     Note: The Equiseta have hollow jointed stems and no true
           leaves. The cuticle often contains siliceous granules,
           so that one species ({E. hyemale) is used for scouring
           and polishing, under the name of Dutch rush or
           scouring rush.
           [1913 Webster]