How the cucumber tendril coils and overwinds.

This paper by Gerbode et al. exemplifies the importance of diversity in advancing science. First, the authors bring to bear diverse perspectives from evolutionary biology, engineering and physics on an age-old question of how cucumber tendrils coil and overwind. Second, they reveal how studying diverse organisms - including what some would consider esoteric tissue, cucumber tendrils - can reveal potential applications for structural engineering.

The problem of cucumber overwinding was first reported by Darwin and has been studied by many plant biologists. The authors use a combination of cell biology and modeling to put forth a new hypothesis. They propose that differential lignification on the inner side of the helical tendril contributes to differential extensibility and overwinding when the tendrils are under tension (stretched). Based on this hypothesis, they predict and replicate overwinding using artificial materials to generate differential extensibility in coils under tension and compression.

The authors indicate that the potential to overwind changes with age in the cucumber tendrils, but not in Passifloraceae tendrils. One explanation might be that lignification or other changes in cell wall structure occur earlier in the Passiflora tendrils, making them more similar to the older cucumber tendrils. Another explanation is that some as yet unidentified factor is the underlying cause of the differential tension in the tendril. From a biological perspective, it will be interesting to determine whether lignification merely correlates positively with overwinding, or whether there is an as yet unknown factor that causes overwinding.