Flax or flaxen is a pale yellowish-gray, the color of straw or unspun dressed flax. The first recorded use of flax as a color name in English was in 1915,Color Sample of Flax: pp. 47, Plate 12, Color Sample B2 but flaxen had been used to describe hair color in David Copperfield, by Charles Dickens in 1849: Mr. Omer's granddaughter, Minnie, is described as "a pretty little girl with long, flaxen, curling hair."
References
See also Lists of colors Flaxen gene