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WordNet
mustard tree
  1. n. 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]