The constitution of calycopterin as 5 ∶ 4′-dihydroxy-3 ∶ 6 ∶ 7 ∶ 8-tetramethoxy-flavone has been confirmed. Calycopterin diethyl ether has been shown to have ethoxyl groups in the 5 and 4′-positions, since on fission with alcoholic alkali, it yieldsp-ethoxy benzoic acid and 2-hydroxy-ω ∶ 3 ∶ 4 ∶ 5-tetramethoxy-6-ethoxy acetophenone. The constitution of the ketone has been established by methylation and comparison with a synthetic sample obtained by the ethylation of ω ∶ 2 ∶ 3 ∶ 4 ∶ 5-pentamethoxy-6-hydroxy-acetophenone.