a plant of the genus sinapis, a pod-bearing, shrub-like plant, growing wild, and also cultivated in gardens
a small mustard plant
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 Israel is the Sinapis nigra (= Brassica nigra). This garden herb sometimes grows to a considerable height, so as to be spoken of as “a tree” as compared with garden herbs.
Is the mustard seed the smallest of seeds?