Plant Structure, Function, and Use

Plant Responses to Stimuli

What are the main plant hormones?

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.”)


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