The walk and jump of Equisetum sporesReport as inadecuate

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1 LIPhy - Laboratoire Interdisciplinaire de Physique Saint Martin d’Hères

Abstract : Equisetum plants horsetails reproduce by producing tiny spherical spores that are typically 50 micrometers in diameter. The spores have four elaters, which are flexible ribbon-like appendages that are initially wrapped around the main spore body, and that deploy upon drying or fold back in humid air. If elaters are believed to help dispersal, the exact mechanism for spore motion remains unclear in the literature. In this manuscript we present observations of the -walks- and -jumps- of Equisetum spores, which are novel types of spore locomotion mechanisms compared to the ones of other spores. Walks are driven by humidity cycles, each cycle inducing a small step in a random direction. The dispersal range from the walk is limited, but the walk provides key steps to either exit the sporangium or to reorient and refold. Jumps occur when the spores suddenly thrust themselves after being tightly folded. They result in a very efficient dispersal: even spores jumping from the ground can catch again the wind, while non-jumping spores stay on ground. The understanding of these movements, which are solely driven by humidity variations, conveys biomimetic inspiration for a new class of self-propelled objects.

Author: Philippe Marmottant - Alexandre Ponomarenko, - Diane Bienaimé, -



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