Cultivated flax, Linum usitatissimum
, is an annual plant that grows erect to a height of 40–120 cm. Its flowers are blue or white. Its stiff stalks contain flax fibers, and oil is extracted from its seeds. After the plant is cut, the stalks are soaked in water, called mei mishra
in the language of the Sages, for several days. Various bacteria cause the materials that attach the fibers to the stalks to decompose. Afterward the shell is beaten and opened and the fibers are extracted to be used in weaving linen, bad
in the language of the Torah. The flax plant has been cultivated since ancient times, especially in ancient Egypt.