Mustard trees, or Salvadora persica, grow about 20 feet tall and wide. Horticulturalists classify the mustard tree as an evergreen shrub with low hanging branches, though it is often trained as a small tree.
Salvadora persica grows predominantly in India, the Middle East and Africa. Different regional names are Toothbrush Tree, Saltbush and Miswak. Camels, sheep and goats forage on the leaves. Salvadora persica produces sweet, edible fruits that are often fermented or dried. Several small studies, including one conducted for the World Health Organization, showed that chewing sticks made from branches of Salvadora persica reduced the need for periodontal care when compared with toothbrush users.