Botanical ratchets

I. M. Kulić, M. Mani, H. Mohrbach, R. Thaokar, L. Mahadevan

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Ratcheting surfaces are a common motif in nature and appear in plant awns and grasses. They are known to proffer selective advantages for seed dispersion and burial. In two simple model experiments, we show that these anisotropically toothed surfaces naturally serve as motion rectifiers and generically move in a unidirectional manner, when subjected to temporally and spatially symmetric excitations of various origins. Using a combination of theory and experiment, we show that a linear relationship between awn length and ratchet efficiency holds under biologically relevant conditions. Grass awns can thus efficiently transform non-equilibrium environmental stresses from such sources as humidity variations into useful work and directed motion using their length as a fluctuation amplifier, yielding a selective advantage to these organelles in many plant species.

Original languageEnglish (US)
Pages (from-to)2243-2247
Number of pages5
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1665
StatePublished - Jun 22 2009


  • Anisotropic surfaces
  • Biological ratchets
  • Transport

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)
  • Environmental Science(all)
  • Agricultural and Biological Sciences(all)

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