water milfoil

from WordNet (r) 3.0 (2006)

water milfoil
    n 1: an aquatic plant of the genus Myriophyllum having feathery
         underwater leaves and small inconspicuous flowers

from The Collaborative International Dictionary of English v.0.48

Milfoil \Mil"foil\, n. [F. mille-feuille, L. millefolium; mille
   thousand + folium leaf. See {Foil} a leaf.] (Bot.)
   A common composite herb ({Achillea Millefolium}) with white
   flowers and finely dissected leaves; yarrow.
   [1913 Webster]

   {Water milfoil} (Bot.), an aquatic herb with dissected leaves
      ({Myriophyllum}).
      [1913 Webster]

from The Collaborative International Dictionary of English v.0.48

Water milfoil \Wa"ter mil"foil\ (Bot.)
   Any plant of the genus {Myriophyllum}, aquatic herbs with
   whorled leaves, the submersed ones pinnately parted into
   capillary divisions.
   [1913 Webster]

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