In the development of "second generation biofuel ethanol" from lignocellulosic biomass, scientists are actively finding ways to break the "recalcitrance" in plant cell walls which is considered as a major barrier against cost-effective "cellulose-ethanol" production. This "recalcitrance" is attributed to the tight lignin wrapping surrounding the well-ordered, crystalline arrangement of cellulose molecules (together with hemicelluloses and pectins) in the plant cell wall. "The chemical and structural characteristics of these plant cell wall constituents remain largely unknown today". Understanding these characteristics can open new doors for the development of better pretreatment methods to break recalcitrance. Scanning probe microscopy techniques can be a powerful tool for understanding the plant wall characteristics which contribute to recalcitrance. John Yarbrough and colleagues in the Chemical and Biosciences Center, National Renewable Energy Center (Colorado, USA) recently reviewed some tools in scanning probe microscopy which can be applied for the characterization of plant cell wall structures in lignocellulosic bioenergy feedstocks. They also discussed "future developments based on scanning probe microscopy techniques that combine linear and nonlinear optical techniques to characterize plant cell wall nanometer-scale structures, specifically aperture-less near-field scanning optical microscopy and coherent anti-Stokes Raman scattering microscopy". A full copy of the review can be accessed in the open access journal website, Biotechnology for Biofuels (URL above)..