Morphometric and mechanical characteristics of Equisetum hyemale stem enhance its vibration

Abstract

Main conclusion The order of the internodes, and their geometry and mechanical characteristics influence the capability of the Equisetum stem to vibrate, potentially stimulating spore liberation at the optimum stress setting along the stem. Equisetum hyemale L. plants represent a special example of cellular solid construction with mechanical stability achieved by a high second moment of area and relatively high resistance against local buckling. We proposed the hypothesis that the order of E. hyemale L. stem internodes, their geometry and mechanical characteristics influence the capability of the stem to vibrate, stimulating spore liberation at the minimum stress setting value along the stem. An analysis of apex vibration was done based on videos presenting the behavior of an Equisetum clump filmed in a wind tunnel and also as a result of excitation by bending the stem by 20°. We compared these data with the vibrations of stems of the same size but deprived of the three topmost internodes. Also, we created a finite element model (FEM), upon which we have based the ‘natural’ stem vibration as a copy of the real object, ‘random’ with reshuffled internodes and ‘uniform’, created as one tube with the characters averaged from all internodes. The natural internode arrangement influences the frequency and amplitude of the apex vibration, maintaining an equal stress distribution in the stem, which may influence the capability for efficient spore spreading.Electronic supplementary materialThe online version of this article (doi:10.1007/s00425-017-2648-1) contains supplementary material, which is available to authorized users.

High-Throughput Analysis of Arabidopsis Stem Vibrations to Identify Mutants With Altered Mechanical Properties

“…Nevertheless, experiments in which each sample was tested at multiple initial angles indicated that ω d was nearly constant, regardless of the initial angle (Table 1 ). A previous study using the stem of Equisetum hyemale demonstrated the effect of nodes on stem vibration (Zajaczkowska et al, 2017 ). Therefore, we also examined the effects of the numbers of nodes on ω d in 10-cm stems of A. thaliana .…”

“…Another problem of measuring free vibration is that a high-speed camera or detector is required to obtain a sufficient resolution from the short-time displacement. Other studies of free vibration of plant stems used cameras with time resolutions of 200–1,000 fps (Der Loughian et al, 2014 ; Villibor et al, 2016 ; Zajaczkowska et al, 2017 ). In this study, we used high-speed shooting at 240 fps with the default function of an iPhone/iPad.…”

“…In vibrational analyses based on videos, coordinates are obtained by tracking a specified target. In previous studies, to capture stem vibrations, the features were tracked by an automatic analysis using the Kineplant-CR toolkit in MATLAB (Der Loughian et al, 2014 ), by a semi-automatic analysis with a free software for tracking (Zajaczkowska et al, 2017 ) or by a manual analysis (Yazdanmanesh and Kalantari, 2015 ). In Spatz and Speck ( 2002 ), vibrations were captured by detecting tape, as a small marker, with the commercial software.…”

“…In Spatz and Speck ( 2002 ), vibrations were captured by detecting tape, as a small marker, with the commercial software. Although it is not certain whether the image analysis was batch processed or ω d was calculated seamlessly in these studies, the numbers of tested samples were relatively small and they did not appear to have high-throughput potential (Spatz and Speck, 2002 ; Der Loughian et al, 2014 ; Yazdanmanesh and Kalantari, 2015 ; Zajaczkowska et al, 2017 ). Currently, the highest throughput method for determining free vibration uses a custom-made device rather than a camera (Zebrowski, 1991 , 1999 ).…”

Comparative analysis of pollen release biomechanics in Thalictrum: implications for evolutionary transitions between animal and wind pollination

“…Vibration is also an important feature in the reproductive ecology of other diverse taxa. For example, an analogous mechanism of resonance vibration occurs in some bryophytes, horsetails and fungi and functions in spore dispersal (Grace, ; Johansson et al ., ; Zajączkowska et al ., ). Pollen release in the c .…”