Maple samaras recover autorotation following raindrop collisions

• 成果类型: Article
• 署名作者: Schaeffer, Breanna M.; Truscott, Tadd T.; Dickerson, Andrew K.
• 署名单位: University of Tennessee System; University of Tennessee Knoxville; King Abdullah University of Science & Technology
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-10597
• DOI: 10.1073/pnas.2422641122
• 发表日期: 2025-02-18
• 关键词: long-distance dispersal; seed dispersal; wind; flight; abscission; mechanisms; capacity

摘要

Samaras are known for their elegant and robust autorotation, a resilience that persistsin the adverse conditions imposed by high-speed raindrops. Like flying insects, samarasdescending from tall trees are likely to be struck by raindrops in an intense storm. In thisstudy, we detail the collision dynamics for impact regions across the samara body andthe drop-shedding mechanisms that samaras exhibit to return to autorotation. Impactsacross the samara body can pitch the samara up to 60 degrees and, in some cases,induce spanwise roll. Raindrops may shatter or remain intact upon impact, pushingthe undamaged samara downward before autorotation is recovered. Drops that strikenear the wingtip elicit the greatest recovery distance, while impacts onto the nutletmass are the least disruptive to the samara and most likely to cause the drop to inducefragmentation. Faster drops allow for quicker drop shedding and a subsequent rapidreturn to autorotation in less than 50 ms. Our results indicate that samaras are robust toraindrop impacts and consistently recover autorotation, resulting in a minor reductionin dispersal distance. To recover, the entire drop is shed from the spinning samara overa time closely tied to the shedding mode and ensuing drop rejection forces.