Mustard: A plant of the genus sinapis, a pod-bearing, shrub-like plant, growing
wild, and also cultivated in gardens. The little round seeds were an
emblem of any small insignificant object. It is not mentioned in the
Old Testament; and in each of the three instances of its occurrence
in the New Testament
(Matthew 13:31,32; Mark 4:31,32; Luke 13:18,19) it is spoken
of only with reference to the smallness of its seed. The common
mustard of Palestine is the Sinapis nigra. This garden herb sometimes
grows to a considerable height, so as to be spoken of as "a tree" as
compared with garden herbs.