MUSTARD (Heb. חַרְדָּל, ḥardal), the name applied to two species, the common mustard (Sinapis alba), known in rabbinical literature as "Egyptian mustard," and the kind called simply "mustard."
The latter was extracted from the seeds of a different botanical genus, Brassica nigra, the mustard prepared from it being darker and more pungent than the former. This species, like white mustard, grows wild in Ereẓ Israel but was also cultivated. Given favorable conditions, the plant reaches a height of more than six feet. The aggadah relates that a man having sown "a single seed of mustard… would climb it as he would a fig tree" (TJ, Pe'ah 7:4, 206). The seed of this species is very small (1–1.6 mm.) and was used to indicate the smallest measure of size (Ber. 31a). The contrast between the size of the plant and the seed is used in a parable in the New Testament (Matt. 13:31). Although these two species of mustard belong to different botanical genera they are very similar in appearance (except that the white mustard plant is smaller and its seed larger). Hence the rule that mustard and Egyptian mustard do not constitute *mixed species (kilayim; Kil. 1:2). Both have conspicuous yellow flowers (cf. Kil. 2:8–9). In Israel there are many species belonging to the family of Cruciferae which have yellow flowers and seeds with a pungent flavor. Among these the species Sinapis arvensis is very widespread. This is called in the Mishnah lafsan ("charlock") and it was laid down that "mustard and charlock, although resembling one another, do constitute kilayim" (Kil. 1:5).
Sources: Encyclopaedia Judaica. © 2008 The Gale Group. All Rights Reserved.