Flax is a group of the bast annual and perennial plants from the Linacease family that form the genus Linum. Several varieties of the species, L. Usitatissimum, are grown primarily for their fiber, used in making Linen Flax, or for their seeds, the source of Linseed oil. Although both types have the same botanical origin, they perform differently due to their selection for different traits over many decades. Linen flax grows taller (0.9 - 1.2 m with a shive diameter of 0.25 - 0.5 cm), branches closer to the top and has smaller seed yield. Linseed flax is shorter (0.3 - 0.6 m), but has increased branching and an increased seed yield

Fibre flax grows best in a cool, moist climate; seed flax prefers a dry environment.

Flax was cultivated by the ancient civilizations of the Middle East, by the Romans, and in medieval Europe, where it was the principal vegetable fiber grown. In the 19th century, cotton textiles largely supplanted linen; the 20th-century DEVELOPMENT of synthetic fibers reduced the need for flax still further. Today, the major producers of fiber flax are France, China, Romania, Poland, Ukraine and Russia. Seed flax is grown in Canada, Argentina, India, China and the United States.

Flax fiber for papermaking has its origin in the residue of the textile industrial sector (as flax in the fiber from which linen is produced) and as flax straw from the manufacturing of seed flax. Textile flax is produced specifically for the fiber content of the plant which is used in the production of the high-value added linen textile products. Waste material generated in the various stages of processing may be directed towards the paper industry. Seed flax straw is the residue of the production and harvest of flax seed, which is used in the broad range of products, e.g., oil base for paints and varnishes and certain varieties as a food additive.

Flax has traditionally been used as the primary furnish for cigarette paper (burning tube), where strength, opacity and control of air permeability are required. Banknote paper often incorporates flax as a component of the furnish, largely to enhance fold and general strength characteristics.