オニバス自生地

Deep within the heart of Tokyo, a hidden wonder awaits: the Onibasu Jibutsuchi, or Euryale ferox natural habitat. This unique sanctuary offers a glimpse into the life of an extraordinary aquatic plant. Onibasu, also known as the prickly water lily or foxnut, is a captivating annual herb with a story to tell. Onibasu’s life begins on the lakebed, where it extends its roots and leaf stalks, preparing for its dramatic emergence. In the summer months, enormous circular leaves unfurl on the water’s surface. Their size can reach up to 2.6 meters in diameter. These leaves are tough, featuring prominent veins and prickles on both sides. As the summer progresses, the Onibasu displays its unique purple flowers. These blossoms often remain closed and submerged, self-pollinating beneath the surface. The flowers that do bloom above water open during the day and close at night. The fruit of the Onibasu is a berry-like sphere covered in spines. It contains numerous ball-shaped seeds that float away when the fruit splits open. These seeds, after a period of dormancy that can last from one to several decades, eventually sink to the lakebed and sprout new life. Interestingly, a dry spell can actually stimulate germination. This explains why Onibasu can be abundant one year and scarce the next. Onibasu’s presence in Japan is threatened. Habitat loss due to environmental changes and land development has led to its designation as a Vulnerable species (VU) on the Environment Ministry’s Red List. While Onibasu was once common, it has become increasingly rare in its natural habitat. Onibasu’s seeds have a long history of human use, particularly in China and India. They are cultivated for consumption and used in traditional medicine. The prickly water lily’s presence here, at the Onibasu Jibutsuchi, reminds us of the delicate balance of nature and the importance of preserving these hidden treasures of the natural world.