NOVELTY - Manufacturing (M1) modified lignin involves conducting a lignin-producing polymerization reaction in the presence of polymerizable monomers selected from flavan-3-ol compounds or gallic acid derivative, where at least one of the polymerizable monomers is incorporated into the resulting lignin.    USE - For manufacturing modified lignin (claimed) useful in biomass processing.    ADVANTAGE - The method has the potential to deliver quantum improvements in biomass processing compared to the more incremental changes that are envisioned from simply perturbing the known lignin monomer pathways; and alters lignin by altering its monomer complement to allow the biomass polysaccharides to be more efficiently and sustainably utilized.    DETAILED DESCRIPTION - Manufacturing (M1) modified lignin involves conducting a lignin-producing polymerization reaction in the presence of polymerizable monomers selected from flavan-3-ol compounds of formulae (I) and (II) or gallic acid derivative of formulae (III), where at least one of the polymerizable monomers is incorporated into the resulting lignin.    R1 and R2=H, =O, hydroxy, alkyloxy, alkanoyl, alkanoyloxy, hydroxy-substituted alkoxy, hydroxy-substituted alkanoyl, hydroxy-substituted alkanoyloxy, benzoyloxy, monosaccharide, disaccharide, gallate ester of monosaccharide, gallate ester of disaccharides, mono-hydroxy-substituted benzoyloxy, di-hydroxy-substituted benzoyloxy or tri-hydroxy-substituted benzoyloxy;    R3-R6=H, hydroxy, alkyl, alkyloxy, hydroxy-substituted alkyl, hydroxy-substituted alkoxy, benzoyloxy, mono-hydroxy-substituted benzoyloxy, di-hydroxy-substituted benzoyloxy or tri-hydroxy-substituted benzoyloxy;    R7-R11=H, hydroxy, alkyl, alkyloxy, hydroxy-substituted alkyl or hydroxy-substituted alkoxy;    R1a-R5a=H, hydroxy, =O, hydroxy, alkyloxy, alkanoyl, alkanoyloxy, hydroxy-substituted alkoxy, hydroxy-substituted alkanoyl, hydroxy-substituted alkanoyloxy, benzoyloxy, mono-hydroxy-substituted benzoyloxy, di-hydroxy-substituted benzoyloxy or tri-hydroxy-substituted benzoyloxy.    Provided that    (1) at least one of R3-R6 is hydroxyl;    (2) at least one of R7-R11 is hydroxyl;    (3) at least one of R1a-R5a is hydroxyl;    (4) R1a-R5a are not simultaneously H.    INDEPENDENT CLAIMS are included for the following:    (1) new isolated cell wall or isolated plant cell containing compounds of formulae (I)-(III) where the compounds (I)-(III) are incorporated into the lignin of the cell wall, or the compound (III) is incorporated into the lignin in cell walls of the isolated plant cell    (2) a modified lignin produced by the method (M1).