01 / Shiratamamo Habitat at Ōike Pond (出羽島大池のシラタマモ自生地)
Lost to reclamation at Hachirōgata,Tebajima became its only habitat.
Shiratamamo (シラタマモ) belongs to a genus of the stonewort family, and this is the only species known in Japan. It was once found at Hachirōgata (八郎潟) in Akita too, but was lost to reclamation, and Tebajima (出羽島) became its only habitat. Ōike Pond has the conditions it needs: two parts seawater to one part fresh, with the sea seeping in between boulders on the shore.
- National Natural Monument (designated Mar. 16, 1972)
- A brackish pond of 1,250 m² in the island's southwest (town)
- Growing condition: seawater 2 to fresh water 1 (Agency for Cultural Affairs)

