Shoot meristems of higher plants are composed of several clonally distinct cell lineages. Periclinal chimeras have been used to determine the fate of derivatives of these lineages in mature leaves and other organs of the plant. Fates of individual meristem cells are not rigidly fixed and the distribution of tissue derived from each meristem lineage in different regions of an organ is variable. The amount of proliferation from an individual lineage can be altered without affecting the overall morphology of organs. Mechanisms exist by which cells from several lineages coordinate their relative amounts of proliferation. The conclusion from these studies is that cell proliferation and organ morphogenesis are developmental events that can be uncoupled.