'mustard tree' definitions:

Evergreen South American shrub naturalized in United States; occasionally responsible for poisoning livestock [syn: tree tobacco, mustard tree, Nicotiana glauca]

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, mustard tree, Salvadora persica]