The use of tissue culture techniques in the study of growth, metabolism, and differentiation has been widely developed for the dicotyledons, but the monocots, especially the grasses, have received little attention. One reason for this was that until recently the establishment of in vitro cultures of monocots was quite difficult. However, this problem was overcome with the discovery that a large concentration of auxin, in comparison to what is used with dicots, would easily induce callus initiation.