Buddleja davidn is a unique biomass that has many attractive agroenergy features, especially its wide range of growth habitat The anatomical characteristics of B davidu were investigated before and after ethanol organosolv pretreatment (one of the leading pretreatment technologies) in order to further understand the alterations that occur to the cellular structure of the biomass which can then be correlated with its enzymatic digestibility Results showed that the ethanol organosolv pretreatment of B davidu selectively removes lignin from the middle lamella (ML), which does not significantly disrupt the crystalline structure of cellulose The removal of ML lignin is a major factor in enhancing enzymatic cellulose to glucose hydrolysis The pretreatment also causes cell deformation, resulting in cracks and breaks in the cell wall These observations, together with characterization analysis of the cell wall poly mer material, lend support to the hypothesis that the physical ditribution of lignin in the biomass matrix is an important structural feature affecting biomass enzymatic digestibility Biotechnol Bioeng 2010 107 795-801 (C) 2010 Wiley Periodicals Inc