Vascular cambium cells divide and grow to produce woody cell types in one direction and phloem cell types in the opposite direction. While both tissues transport water and nutrients, wood has the additional function of providing physical support to the growing stem. The goal of the Mähönen group is to elucidate the molecular mechanisms underlying the bidirectional production of wood and phloem by the vascular cambium, by using Arabidopsis thaliana root and hybrid aspen stem as models. Woody tissue supports not only the canopy of individual trees, but also the structure of entire forests and the ecosystems they sustain. Wood is also a major carbon sink and an essential raw material for industry.