Many hormones control plants—all that help coordinate growth, development, and responses to environmental stimuli. The major ones are auxins (helps in growth, such as growing a plant upward rather than laterally), gibberellins (promote stem and leaf elongation), cytokinins (stimulate cytokinesis [dividing of the cytoplasm] and cell division), ethylene (promotes fruit ripening), and absicisic acid (inhibits growth, such as during a drought). (For more about plant hormones and their discoverers, see the chapter “Plant Diversity.”)