Throughout history, the color purple has been closely associated with nobility in cultures around the world, and Japan is no exception. However, the unique murasaki hue, synonymous with the native gromwell plant, is now under threat as this plant has become an endangered species.
The decline of murasaki can be attributed in part to diseases and cross-breeding with non-native species. In response to this growing demise, a research group led by Kyoto University is spearheading a movement to raise awareness about the importance of gromwell in preserving Japanese culture. As part of ongoing murasaki revival projects across Japan, researchers are investigating the origins of gromwell seeds and educating the public about the significance of protecting the plant’s homogeneity.
The team’s paper was published on May 18, 2023, in the journal Plant and Cell Physiology. Lead author Kazufumi Yazaki emphasizes that various non-profit organizations involved in the gromwell revival are committed to maintaining the silk staining technique through collaboration with plant scientists.
Purple gromwell, scientifically known as Lithospermum erythrorhizon, contains shikonin derivatives in its root surfaces, which are red naphthoquinones. These natural pigments and medicinal properties are deeply rooted in ancient East Asian traditions. Among the various shades of purple dye, the dark purple hue was highly sought after and reserved for members of the highest levels of government, the Imperial family, and the most esteemed Buddhist monks.
Co-author Ryosuke Munakata from Kyoto University’s Research Institute for Sustainable Humanosphere explains that the purple color was also used for a national treasure called Koku-Bun-Ji Kyo. This treasure consisted of ten-volume Buddhist scripture papers on which letters were written with gold.
Furthermore, the gromwell root has been used medicinally for centuries. It is prescribed in various remedies, particularly as an ointment called Shi-Un-Koh, which is still popular today for treating hemorrhoids, burns, frostbite, and other wounds.
Recovery initiatives, such as the Mitaka Gromwell Restoration Project, are focused on ensuring the survival of the native gromwell. The plant’s future is uncertain due to the cucumber mosaic virus spread and sudden environmental changes. Another contributing factor is the cross-breeding with the European species L officinale.
Unexpectedly, official wooden documents excavated from Kyushu and found to have been used to transport cargo during the Asuka dynasty are also related to gromwell. These documents highlight the crucial administrative role played by gromwell’s purple dye.
Co-author Emi Ito from Ochanomizu University expresses hope that their research will raise awareness about the significance of murasaki in Japanese history and culture.
Source: Kyoto University