Given their subterranean existence, roots could be considered among the most inaccessible organs for biological study. Fortunately, roots are extremely amenable to growth in the absence of soil; currently, Arabidopsis thaliana seedlings are extensively studied in non-soil media. is dicotyledonous seedling has several attributes that facilitate studies of root biology including rapid germination, small size, and simple root architecture. By the late 1980s, Arabidopsis was being widely used as a research model for plant biology. e Arabidopsis root was emerging as a particularly powerful and elegant model in cellular and organ developmental biology and environmental response. In the decade prior to publication of the Arabidopsis genome, functionally important molecules in root biology were identied through genetic screens. However, the diculty of cloning the identied loci was a signicant roadblock in understanding the molecular mechanisms driving root growth and development. e attributes that initially made the Arabidopsis root a good physiological and developmental model organ have made it invaluable in the genomics era.