Despite the importance of the vascular cambium in plant biology and in wood production, the molecular and cellular mechanisms underlying cambial activity remain largely unknown. Particularly, it is unknown where the cambial stem cells are located, and how the stem cell niche is organized to drive cambial growth.In animal stem cell studies lineage tracing has been the method for locating the stem cells. In this method single cell clones marked with reporter expression are generated within a population of dividing cells. The clones are transmitted to all daughter cells of the initial cell, resulting in a marked sector within the tissue. By analysing the size and distribution of the sectors the position and the mitotic activity of dividing cells and stem cells can be deduced. In order to understand the cell lineage relations in the Arabidopsis root cambium, we generated GUS/GFP sectors by using two step CRE-lox based clonal activation system. To understand which cells in the primary tissue contribute to the cambium formation we induced single cell clones during the primary development of the root and analysed the growing sectors during the secondary development. We also generated marked sectors in active cambium to map the position of stem cells and to understand the growth dynamics of the cambial cells. In my seminar presentation I will explain how we are utilizing the lineage tracing data to provide mechanistic understanding of cambium regulation.