Source : Webster's Revised Unabridged Dictionary (1913)

Flag \Flag\, n. [From {Flag} to hang loose, to bend down.]
   (Bot.)
   An aquatic plant, with long, ensiform leaves, belonging to
   either of the genera {Iris} and {Acorus}.

   {Cooper's flag}, the cat-tail ({Typha latifolia}), the long
      leaves of which are placed between the staves of barrels
      to make the latter water-tight.

   {Corn flag}. See under 2d {Corn}.

   {Flag broom}, a coarse of broom, originally made of flags or
      rushes.

   {Flag root}, the root of the sweet flag.

   {Sweet flag}. See {Calamus}, n., 2.