markweed

from WordNet (r) 3.0 (2006)

markweed
    n 1: climbing plant common in eastern and central United States
         with ternate leaves and greenish flowers followed by white
         berries; yields an irritating oil that causes a rash on
         contact [syn: {poison ivy}, {markweed}, {poison mercury},
         {poison oak}, {Toxicodendron radicans}, {Rhus radicans}]

from The Collaborative International Dictionary of English v.0.48

markweed \markweed\ n.
   A climbing plant ({Toxicodendron radicans}) common in eastern
   and central U. S. with ternate leaves and greenish flowers
   followed by white berries. It yields an irritating oil that
   causes a rash on contact; commonly called {poison ivy}.

   Syn: poison ivy, poison mercury, poison oak, {Toxicodendron
        radicans}, {Rhus radicans}.
        [WordNet 1.5]