Knotgrass

from WordNet (r) 3.0 (2006)

knotgrass
    n 1: low-growing weedy grass with spikelets along the leaf stems
         [syn: {knotgrass}, {Paspalum distichum}]

from The Collaborative International Dictionary of English v.0.48

Knotgrass \Knot"grass`\, n. (Bot.)
   (a) a common weed with jointed stems {(Polygonum aviculare)};
       knotweed.
   (b) The dog grass. See under {Dog}.
       [1913 Webster]

   Note: An infusion of {Polygonum aviculare} was once supposed
         to have the effect of stopping the growth of an animal,
         and hence it was called, as by Shakespeare, "hindering
         knotgrass."
         [1913 Webster]

               We want a boy extremely for this function,
               Kept under for a year with milk and knotgrass.
                                                  --Beau. & Fl.
         [1913 Webster]