Making Auxin Visible (IMAGE) Universität Bayreuth Caption Seedling of thale cress (Arabidopsis thaliana). The magnifying glass shows the root tip. The cell nuclei are coloured from blue to green and yellow to red as the amount of auxin increases. Most of the auxin is located where the inclination (gravitational vector) is greatest. Below: the chemical structure of auxin. Credit Graphic: S. Shanmugaratnam, A.C. Stiel, M. Kolb. Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.