How the pine seeds attach to/detach from the pine cone scale?

Kahye Song,Shyr-Shea Chang,Sang Joon Lee

doi:10.1080/21553769.2017.1287777

Kahye Song, Shyr-Shea Chang + Show 1 more

Open Access

https://doi.org/10.1080/21553769.2017.1287777

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Abstract

ABSTRACTOne of the primary purposes of pine cones is the protection and distant dispersal of pine seeds. Pine cones open and release their embedded seeds on dry and windy days for long-distance dispersal. In this study, how the pine seeds attach to/detach from the pine cone scale for efficient seed dispersal was experimentally investigated by using an X-ray micro-imaging technique. The cone and seeds adhere to each other in the presence of water, which could be explained by the surface tension and the contact angle hysteresis. Otherwise, without water, the waterproof seed wing surface permits rapid drying for detach and dispersion. On the other hand, during wildfires, pine cones open their seed racks and detach the pine seeds from pine cones for rapid seed dispersal. Due to these structural advantages, pine seeds are released safely and efficiently in normal conditions. These advantageous structures could be mimicked in practical applications.

Highlights

Species reproduction and propagation are the most important objectives of every living organism, and pine trees propagate their species effectively with pine cone
We examined the relation between pine cones and seeds with regard to what kinds of advantageous structure do they have for efficient dispersal
In spite of helpful pine seed shape for long-distance dispersal, unsuitable environmental conditions lead to shortrange dispersal that can result in a critical situation for both the parent tree and the seeds

Summary

Introduction

Species reproduction and propagation are the most important objectives of every living organism, and pine trees propagate their species effectively with pine cone. Pine cones fold their scales, which prevent the seeds from spreading under wet condition. As a result of these structures and movements, the seeds are dispersed far from the parent tree, which enhances the survival of species. The asymmetric fibril orientation converts local swelling and shrinking into global bending movements (Reyssat & Mahadevan 2009). This change occurs in a finely tuned manner. Dawson et al reported that hygroscopic expansion coefficient (0.06 ± 0.02 in their experiment) of fiber in the cone is significantly lower than that of the sclereids (0.20 ± 0.04 in their experiment) for only a 1% change in relative humidity at 23°C (1997). The stiffness and expansion coefficients of each layer are functions of the component compositions and the microfibrill angle with respect to the cell axis (Skaar 1988)

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