Cellulosic biomass is a low-cost feedstock with the potential of costing $40/ton competitive with oil at about $13/barrel on an equivalent energy content basis. These materials must be pretreated prior to biological steps of adding enzymes for scaccharification of cellulose or hemicelluloses as yields are too low otherwise to be economically competitive. Promising new approaches, like ionic liquid solvents, are still in their infancy and need further exploration before implementation at biorefinery levels. Quantifying and imaging the mechanism and efficiency of the ionic liquid pretreatment process is thus a critical first step in developing a pretreatment process that minimize the formation of by-products that are inhibitory to fermentation of cellulosic sugars to ethanol. We evaluated a targeted combination of an ionic liquid (1-n-Ethyl-3-methylimidazolium Acetate) with a leading candidate for national energy crop production (switchgrass) to evaluate the efficacy of ionic liquid in breaking down biomass into fundamental biological building blocks.  In this study, auto-fluorescent lignin mapping and its de-convolution was used to visualize cellulose in pristine switchgrass stems in order to gain unprecedented cellular level understanding and insight of biomass dissolution during ionic liquid pretreatment.  Ionic liquid efficiently solubilized both cellulose and lignin.  Cell wall swelling, perhaps due to breakage of inter and intra-molecular hydrogen bonding between cellulose fibrils and lignin, followed by complete dissolution of biomass was observed without using chemicals routinely used in staining, embedding and processing of biomass.   In comparison to untreated biomass, ionic liquid pretreated biomass provides enhanced area enabling efficient saccharification with high sugar yields.