Auxin is a hormone found in plants that induces growth and fructification even if the plant hasn't been pollinated (seedless watermelon is an example).
Auxin is also responsible for phototrophism which is the bending toward light sources. Used in high doses, it stimulates the production of ethylene which stops the growth and may cause leaves to fall and can kill the plant.
Fact-index.com financially supports the Wikimedia Foundation. Displaying this page does not burden Wikipedia hardware resources. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.