title: The fern sporangium: a unique catapult.
abstract: Various plants and fungi have evolved ingenious devices to disperse their spores. One such mechanism is the cavitation-triggered catapult of fern sporangia. The spherical sporangia enclosing the spores are equipped with a row of 12 to 13 specialized cells, the annulus. When dehydrating, these cells induce a dramatic change of curvature in the sporangium, which is released abruptly after the cavitation of the annulus cells. The entire ejection process is reminiscent of human-made catapults with one notable exception: The sporangia lack the crossbar that arrests the catapult arm in its returning motion. We show that much of the sophistication and efficiency of the ejection mechanism lies in the two very different time scales associated with the annulus closure.
authors.affiliation: Université de Nice Sophia Antipolis (UNS), Laboratoire de Physique de la Matière Condensée, CNRS UMR 7336, Nice, France. xavier.noblin@unice.fr
authors.forename: X
authors.initials: X
authors.lastname: Noblin
authors.forename: N O
authors.initials: NO
authors.lastname: Rojas
authors.forename: J
authors.initials: J
authors.lastname: Westbrook
authors.forename: C
authors.initials: C
authors.lastname: Llorens
authors.forename: M
authors.initials: M
authors.lastname: Argentina
authors.forename: J
authors.initials: J
authors.lastname: Dumais
mesh_terms: D048430:Cell Shape; D004548:Elasticity; D032494:Polypodium / Q000166:cytology / Q000502:physiology*; D058432:Sporangia / Q000166:cytology / Q000502:physiology*; D013170:Spores / Q000502:physiology*; D014867:Water
chemical_list: D014867:Water