Between the cracks in the sidewalk sprouts a thin, green stem with fragile white flowers. It is overlooked by the masses of people who walk past it each day. Unknown to these individuals, however, is the significance of the Arabidopsis plant within the scientific community. In her lab, Prof. Adrienne Roeder, a Nancy M. and Samuel C. Fleming Term Assistant Professor at the Weill Institute for Cell and Molecular Biology, uses the Arabidopsis sepal as a model system to study the spatial and temporal development of cells. Sepals are the part of the plant that encloses the flower.