Mentioned along with the cumin at Isaiah 28:25, 27 is the plant described by the Hebrew word qeʹtsach. It has been variously identified by translators as “fitches” (KJ), “fennel” (Mo), and “dill” (AT; RS); but “black cumin” (JP; NW) seems to be favored by the context and also by the corresponding name in Arabic (qazha). Despite its English name, black cumin (Nigella sativa) is not classified botanically with the cumin plant, and though known as “the nutmeg flower,” it likewise differs from the cultivated nutmeg. It is of the Ranunculaceae (buttercup) family, grows to about the same height as the cumin, has similar feathery leaves, but blossoms with individual, attractive flowers with white to blue petals. The seed vessels have interior compartments, and the tiny black seeds, smaller than the cumin, are acrid as well as aromatic and are used on foods as a rather peppery seasoning. It was a favorite spice of the ancient Greeks and Romans.​—PICTURE, Vol. 1, p. 543.

Though neither the cumin nor the black cumin is widely cultivated in the region of Palestine today, in Bible times they both were more popular there.

He likewise shows that after harvesting, the threshing of the seeds of the cumin and black cumin plants was not done with heavy wheels or rollers of threshing instruments, but was accomplished by beating the seed capsules with a staff or, for the stouter pods of the black cumin, a rod so the small tender seeds would not be damaged.