Source : Webster's Revised Unabridged Dictionary (1913)

Pipewort \Pipe"wort`\, n. (Bot.)
   Any plant of a genus ({Eriocaulon}) of aquatic or marsh herbs
   with soft grass-like leaves.

Source : WordNet®

pipewort
     n : aquatic perennial of North America and Ireland and Hebrides
         having translucent green leaves in a basal spiral and
         dense buttonlike racemes of minute white flowers [syn: {Eriocaulon
         aquaticum}]