A in plant cell is a complex amorphous polymer and it is   from three aromatic alcohols, namely [https://pubchem.ncbi.nlm.nih.gov/compound/p-Coumaryl-alcohol P-Coumaryl], [https://pubchem.ncbi.nlm.nih.gov/compound/Coniferyl-alcohol Coniferyl], and [https://pubchem.ncbi.nlm.nih.gov/compound/Sinapyl-alcohol Sinapyl] alcohols. Lignin is a highly branched polymer and accounts for 15-30% by weight of , so the structure of lignin will vary significantly according to the type of LCBM and the composition will depend on the degradation process. This biosynthesis process is mainly consists of radical coupling reactions and it generates a particular lignin polymer in each plant species. So due to having a complex structure, various molecular spectroscopic methods have been applied to resolve the aromatic units and different interunit linkages in lignin from distinct plant species.