Peak values of twist‐to‐bend ratio in triangular flower stalks of Carex pendula : : a study on biomechanics and functional morphology

Abstract: Premise
Because of their own weight and additional wind forces, plants are exposed to various bending and torsional loads that sometimes require contradictory structural characteristics and mechanical properties. The resulting trade‐off between flexural and torsional rigidity can be quantified and compared using the dimensionless twist‐to‐bend ratio.

Methods
The flexural rigidity of the stems of Carex pendula was determined by 2‐point bending tests. Additionally, 4‐point bending tests and torsional tests were carried out on segments of two internodes directly below the inflorescences to measure flexural and torsional rigidity. Anatomical investigations were performed to quantify the cross‐sectional distribution of their tissues.

Results
The flexural rigidity of the stems, segments of the apical internode 1, and the more basal internode 2 differed significantly from each other, whereas the bending elastic moduli were not significantly different. The torsional rigidity of segments of internode 2 was a factor of 3.3 higher than that of internode 1, whereas the torsional moduli did not differ significantly. The twist‐to‐bend ratios of segments of internode 1 and 2 reached values between 85 and 403. Light microscopic investigations revealed a triangular stem possessing individual sclerenchyma strands, with internode 2 having significantly more strands than internode 1.

Conclusions
In the case of Carex pendula, flexural and torsional rigidity are adapted to the given mechanical constraints by significant changes in morphometric variables (axial and polar second moment of area, number of sclerenchyma strands), whereas the material properties (bending and torsional modulus) do not change markedly along the stem

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch
• Notes: American journal of botany. - 107, 11 (2020) , 1588-1596, ISSN: 1537-2197

Contributors, Places and Time

• Event: Veröffentlichung
• (where): Freiburg
• (who): Universität
• (when): 2020
• Creator: Speck, Olga ; Steinhart, Feray ; Speck, Thomas

Further information

• DOI: 10.1002/ajb2.1558
• URN: urn:nbn:de:bsz:25-freidok-1702205
• Rights: Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 25.03.2025, 1:54 PM CET