Allelopathy: Definition & Examples

Instructor: Ebony Potts

Ebony has taught middle and high school physical science, life science & biology. She's also been an assistant principal and has a doctorate in educational administration.

Have you ever heard of allelopathy? Most people have not, but it is a very powerful and helpful process that helps plants survive. In this lesson you will learn about allelopathy and be introduced to some allelopathic plants.


Rosa has been practicing all summer. The moment she has been waiting for has arrived: basketball try-outs. She's worked hard on her dribble, her shooting, and her passing, but there is still no guarantee she'll make the team. What if there was a way to make sure that the competition was not so tough? What if Rosa could make some of the competition disappear by causing them to miss shots or passes? Then she would stand out and definitely make the team. But there is no way to do that, since there are twenty spots on the team and fifty girls vying for the limited spots. This situation makes Rosa think about something her AP Biology teacher recently talked about, a process called allelopathy. If only she was a rhododendron, she could stop the competition in its tracks!

What is Allelopathy?

Why was Rosa wishing to be a rhododendron? What does a rhodedendron have to do with Rosa and her wish to make the basketball team? Rhodedendron and some other plants possess allelopathic properties. Allelopathy is the biological process in which plants are able to suppress the growth of other plants near them. Some plants are able to do this by releasing chemicals in their leaves as they fall and decompose or by releasing allelopathic chemicals from their roots. These allelopathic chemicals keep new plant species from being able to germinate, or are toxic to the plant after it germinates near them. Once these chemicals are in the soil, they have a prolonged effect that at times can outlive the plant that produced them.

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