Source : Webster's Revised Unabridged Dictionary (1913)

Rosinweed \Ros"in*weed`\, n. (Bot.)
   (a) The compass plant. See under {Compass}.
   (b) A name given in California to various composite plants
       which secrete resins or have a resinous smell.

Source : WordNet®

rosinweed
     n 1: North American perennial having a resinous odor and yellow
          flowers [syn: {Silphium laciniatum}]
     2: any of various western American plants of the genus
        Grindelia having resinous leaves and stems formerly used
        medicinally; often poisonous to livestock [syn: {gumweed},
         {gum plant}, {tarweed}]