Roots of Arabidopsis wild-type (D1 and D2) and miz1 (E1 and E2) growing in a chamber with low water concentration. Image from Kobayashi, A., A. Takahashi, Y. Kakimoto, Y. Miyazawa, N. Fujii, A. Higashitani, and H. Takahashi. 2007. A gene essential for hydrotropism in roots. Proceedings of the National Academy of Sciences of the United States of America 104: 4724–4729.