◆Research findings by a group led by Associate Professor Michiharu Nakano of the Department of Agricultural Sciences in the Faculty of Natural Sciences have been published in the scientific journal *Journal of Experimental Botany*
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The secret behind why the leaves of the endangered dwarf cycad—which lacks blue pigments—appear blue has been uncovered!
A research group led by Associate Professor Michiharu Nakano of the Department of Agriculture, Faculty of Natural Sciences, Kochi University, has uncovered the secret behind why the leaves of the endangered species *Himeonisonotetsu*—which lacks blue pigments—appear blue.It was found that the blue appearance results from a synergistic effect between “structural color (*1)” caused by microscopic wax crystals approximately 0.1 micrometers in diameter on the leaf surface, and the suppression of light scattering by the dark green photosynthetic tissue rich in chlorophyll.
Furthermore, it has been discovered that the wax crystals produced by the dwarf cycas not only appear blue but also strongly reflect ultraviolet light, and they are expected to contribute to material development through biomimetic approaches (*2).
These research findings were published in the British scientific journal *Journal of Experimental Botany* on May 14, 2025.
*1 Structural color
This refers to colors produced by the microscopic structure of an object, even in the absence of pigments. Examples include the blue color of a morpho butterfly’s wings and the iridescent colors of soap bubbles. When light interacts with the microscopic structures on an object’s surface, certain colors are emphasized, causing the object to appear as a specific color.
*2 Biomimicry
This refers to the development of new technologies and products inspired by the remarkable structures and functions found in living organisms. For example, inspired by the microscopic nanostructures found in the wings of the Morpho butterfly, a technology was developed that creates color using these nanostructures without the need for pigments. This technology has led to new printing methods that offer long-lasting color and reduce environmental impact.
[Paper Information]
Title: Structural Coloration and Epicuticular Wax Properties of the Distinctive Glaucous Leaves of Encephalartos horridus
Author: Gaku Nobusawa (Graduate School of Integrated Life Sciences, Hiroshima University; First Author, Corresponding Author)
Taku Okamoto (Graduate School of Information Science and Engineering, Kyushu Institute of Technology)
Michiharu Nakano (Department of Agriculture, Division of Natural Sciences, Faculty of Education and Research, Kochi University)
Makoto Kusaba (Graduate School of Integrated Life Sciences, Hiroshima University)
Published in: Journal of Experimental Botany