Source : WordNet®

mustard tree
     n 1: evergreen South American shrub naturalized in United States;
          occasionally responsible for poisoning livestock [syn: {tree
          tobacco}, {Nicotiana glauca}]
     2: glabrous or pubescent evergreen shrub or tree of the genus
        Salvadora; twigs are fibrous and in some parts of the
        world are bound together in clusters and used as a
        toothbrush; shoots are used as camel fodder; plant ash
        provides salt [syn: {toothbrush tree}, {Salvadora persica}]