Methods for altering the N-glycosylation pattern of proteins in higher plants are provided. In some embodiments, the methods comprise introducing into a duckweed plant a recombinant RNAi construct that provides for the inhibition of expression of α1,3-fucosyltransferase (FucT) and β1,2-xylosyltransferase (XylT). Use of these RNAi constructs to inhibit or suppress expression of both of these enzymes, and isoforms thereof, advantageously provides for the production of endogenous and heterologous proteins having a “humanized” N-glycosylation pattern without impacting plant growth and development. Stably transformed higher plants, including duckweed plants, having this protein N-glycosylation pattern are provided. Glycoprotein compositions, including monoclonal antibody compositions, having substantially homogeneous glycosylation profiles, and which are substantially homogeneous for the G0 glycoform, are also provided.