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)

The Private Life of PlantsOctober 25, 2016
David Attenborough

“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.” (Hughes 1990:19)

Magazine article
Antelope activate the acacia's alarm system