Hakone Sanshobara was added to Your Favorites!
Fuji-Hakone-Izu NP, Kanagawa / Shizuoka
Claim this place to tell your story your way.
Unlike a compact garden rose, Sanshobara can grow into a small tree about 5 m tall. Hakone's garden guide says its trunk is among the largest in the rose family, and its wild flowers reach 5–6 cm across.
Each Sanshobara flower lasts just one day: it opens in the morning and is already dropping by evening. Its early-summer display is made up of these brief, pale-pink appearances.
Researchers described Sanshobara's leaf-gall wasp as a new species in 2023, naming it Diplolepis ogawai for collector Haruo Ogawa. Two parasitoid wasps depend on it—a tiny food web anchored to one rose.
Most native Japanese wild roses have smooth fruits, but Sanshobara's are covered in hard spines. Museum botanists say they still don't know how this prickly rose spreads its seeds.
Its leaves resemble those of sanshō, Japanese pepper, which inspired the name. But Sanshobara is a true rose; sanshō belongs to the citrus family. The namesake is a look-alike, not a close relative.
Hakone selected this wild rose as its town flower on August 2, 1976. The emblem is officially called Hakone-bara, while its familiar Japanese name is Sanshobara.
This isn't a rose scattered across Japan: Rosa hirtula is naturally found only in the Fuji–Hakone area. Japan's 2025 national Red List places it in the Near Threatened category.
The rust fungus on Sanshobara was once thought to be a common rose pathogen. Research showed it was new to science and infects only this rose; it was named Phragmidium satoanum in 2019.
