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Mechanical limits shape the eccentric form of rose prickles
Sabrina Gennis1, Matteo Pezzulla2, Kaare H Jensen1
1Department of Physics, Technical University of Denmark , Kgs. Lyngby, Denmark.
Journal of the Royal Society, Interface
|August 11, 2026
Summary
Rose prickles have an unusual oval shape, unlike typical circular stingers. This morphology is driven by a mechanical trade-off, optimizing cutting ability while preventing buckling, crucial for plant defense.
Area of Science:
- Biomechanics
- Plant Morphology
- Materials Science
Background:
- Rose prickles possess a unique oval cross-section, differing from the circular shapes of many natural and artificial stingers.
- The evolutionary or functional reasons behind this distinct prickle morphology remain largely unexplored.
Purpose of the Study:
- To investigate the hypothesis that rose prickle morphology is constrained by physical trade-offs between bending, buckling, and cutting.
- To understand the mechanical principles underlying the functional morphology of rose prickles.
Main Methods:
- Experiments were conducted using polydimethylsiloxane (silicone) stingers with varied cross-sectional shapes.
- These stingers were used to lacerate a gelatin material simulating skin to analyze cutting mechanics.
Main Results:
- Circular stingers primarily cause superficial scratches due to bending.
- Prickles with a moderate aspect ratio demonstrated enhanced cutting ability and mechanical stability.
- Excessively narrow prickles showed a tendency to weaken and buckle, compromising their cutting function.
- The optimal aspect ratio for minimizing unfavorable mechanics was found to be between 2 and 4, aligning with biological observations (2.7±0.7).
Conclusions:
- A novel mechanical trade-off involving bending, buckling, and cutting influences rose prickle morphology.
- Cutting mechanics represent a significant potential driver for the evolution of the rose prickle's unique shape.
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