Luteolin is a flavone, a type of flavonoid, with a yellow crystalline appearance. Luteolin is the principal yellow dye compound that is obtained from the plant Reseda luteola, which has been used as a source of the dye since at least the first millennium B.C. Luteolin was first isolated in pure form, and named, in 1829 by the French chemist Michel Eugène Chevreul. The luteolin empirical formula was determined by the Austrian chemists Heinrich Hlasiwetz and Leopold Pfaundler in 1864. In 1896, the English chemist Arthur George Perkin proposed the correct structure for luteolin. Perkin's proposed structure for luteolin was confirmed in 1900 when the Polish-Swiss chemist Stanislaw Kostanecki (1860–1910) and his students A. Różycki and J. Tambor synthesized luteolin.