Source : WordNet®

white thistle
     n 1: any plant of the genus Argemone having large white or yellow
          flowers and prickly leaves and stems and pods; chiefly
          of tropical America [syn: {prickly poppy}, {argemone}, {devil's
          fig}]
     2: spiny shrub with silvery-scurfy foliage of alkaline plains
        of southwestern United States and Mexico [syn: {quail bush},
         {quail brush}, {Atriplex lentiformis}]