02022-12-20 | Environment | 2 comments

The German language has the phrase empfindlich wie eine Mimose sein – to be as sensitive as a Mimosa. This plant is known by many common names including sensitive plant, humble plant, shameplant, and touch-me-not. Find out more about the Mimosa plant on Wikipedia.

James Bridle recounts an experiment, also mentioned in the above-linked Wikipedia article, by researcher Monica Gagliano.

…she devised a simple mechanism: a cup attached to a vertical rail which, when released, would drop a mimosa in its pot exactly fifteen centimetres onto a foam pad. The soft thonk of this landing was enough to surprise the plant into closing up its leaves, but not enough to damage it: a scientifically precise stimulus, with a measurable, ecologically relevant response. Mimosa leaves have small hydraulic structures at their base which, by pumping or draining water, allow them to expand and contract, forcing the leaves to curl. The curling is understood to be a response to a threat: either from animal predation, or excessive heat and evaporation.


She kept dropping the plants, over and over again, up to sixty times a session, over multiple sessions. Three hundred and sixty drops a day: a marathon of bumps and shocks. Thonk thonk thonk. It transpired that it only took a few drops – as few as four or five – for the plants to realize that there was no threat, and that it was safe to keep their leaves open (a side test, involving a different stimulus which still elicited the closing response, revealed that they weren’t simply exhausted by the activity). By the end of the sixty-drop sessions, the plants were entirely unbothered by the drop: they had learned to ignore it.

Here is where it becomes interesting:

Gagliano and her colleagues rested and then retested individual mimosas, demonstrating that they retained over time the memory of the drop, and their associated change in behaviour. Mimosas – and, we must now understand, all plants – are not machines. They are more than the sum of a set of pre-programmed actions and reactions. They learn, remember and change their behaviour in response to the world.

Excerpt from Ways of Being by James Bridle


  1. luna

    Beautiful. So there is hope for us humans too in healing-transforming our old uncomfortable habit responses to old traumas into New Upgraded FeelingGood habit responses……as technically we are made of the same “stuff”as mimosas, just different molecular structures……nice!

  2. JaneParham

    Oh, Ottmar, I love it when you speak German! :-)

    One of my division chiefs at NASA Headquarters was Dr. Terri Lomax, who has made her award-winning reputation on the study of tomatoes’ responses to environmental changes, especially while flying in the very low gravity of space. Gravity plays a large role in the behavior of plants, as well as animals and all of us. Remove gravity and weird things happen. From a study:

    “Plant growth and development is regulated by changes in environmental signals. Plants sense environmental changes and respond to them by modifying gene expression programs to adjust cell growth, differentiation, and metabolism.” Terri inspired you to respect the intelligence of tomatoes!

    Another NASA friend of mine, Volker Kern, spent his time studying the effects of low gravity on moss, which starts growing upside-down in space.

    Thank goodness scientists are not excited about political opinions or any cuckoo theories, except for possible defunding of their projects. They are too busy in their labs proving and disproving real theories.


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