SUMMARYThe common opinion that cellulose microfibril deposition in cell walls of meristematic cells is random will have to be revised. In tunica, corpus and rib meristem cells ofPetunia hybridaandVinca majormicrofibrils are deposited in parallel arrays. The cell walls of corpus cells consist of lamellae. Each lamella has a different microfibril orientation. As a consequence, the random distribution of cortical microtubules found in corpus cells (Sakaguchiet al.1988) bear no direct relation to the parallel deposition of cellulose microfibrils in the walls of these cells.