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  • Strategy

Leaves signal presence of predators: acacia


Acacia erubescens / Rotational / LicensePD - Public Domain

The leaves of acacias send a warning to other plants that herbivores are feeding by releasing ethylene gas.

"The African acacias, well-protected though they may be by their thorns, use distasteful chemicals in their leaves as a second line of defence. Furthermore, and most remarkably, they warn one another that they are doing so. At the same time as they fill their leaves with poison, they release ethylene gas which drifts out of the pores of their leaves. Other acacias within fifty yards are able to detect this and as soon as they do so, they themselves begin to manufacture poison and distribute it to their leaves." (Attenborough 1995:70)

Wouter Van Hoven, a zoologist from Pretoria University, documented the death of kudus in an area where they were restricted in movement during a drought. He found that the kudus died due to chemicals released by acacia. He also noticed that giraffes, who could roam freely, browsed only on one acacia in ten, avoiding those trees that were downwind. (see Hughes 1990:19)

Acacia damaged by browsing giraffes release a chemical alert to downwind trees. Giraffes select upwind trees for subsequent dining. Artist: Emily Harrington. Copyright: All rights reserved. See gallery for details.

About the inspiring organism
Med_800pxacacia_erubescens00 Acacia

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Organism/taxonomy data provided by:
Species 2000 & ITIS Catalogue of Life: 2008 Annual Checklist

Bioinspired products and application ideas

Application Ideas: Product that inhibits release of ethylene gas from stored food.

Industrial Sector(s) interested in this strategy: Agriculture, food storage

Attenborough, D. 1995. The Private Life of Plants: A Natural History of Plant Behavior. London: BBC Books. 320 p.
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Hughes S. Antelope activate the acacia's alarm system. New Scientist. 1736: 19.
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over 3 years ago
View the text from the New Scientist article here: This article mentions how giraffes browse only on one acacia tree in ten, avoiding those trees which are downwind.
over 3 years ago
This video on YouTube, Mind of Plants, talks about research that revealed this strategy. It resulted from deaths of kudus during a drought when they fed on the acacia and died. The information is seen in minutes 1-7 and 22:20-26:
over 6 years ago
Thanks to Duarte Miguel Prazeres for finding and uploading this photo.
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