Once we start coloring our hair, we may be surprised to learn that we begin to have a problem in common with plant biologists: finding the right dye for our roots. In the case of the biologists, just the right chemical is needed to measure exactly how plant roots grow. Now, a researcher at the Salk Institute has discovered a fluorescent dye that, paired with other imaging techniques, reveals root growth to be influenced by a major plant hormone more than previously thought.