Note: Information is dated. Do not rely on it.Flax. An important fiber and seed plant belonging to the order Linaceae. The common flax (Linum usitatissimum), an annual plant, grows wild in western Asia between the Persian Gulf and the Caspian Sea. It has been cultivated since remote antiquity in the Old World, and is now widely diffused in the New. The short fiber, or tow, is used in making rope, and the longer fiber for making linen thread and fabrics. The essentials of preparing flax fiber are found depicted on the tombs of the ancient Egyptians who wrapped the bodies of mummies in linen cloth. Flaxseed, the source of linseed oil, is a valuable article of commerce.