Rheum officinale (English spelling)

Japanese: ダイオウ(大黄) - ダイオウ（英語表記）Rheum officinale

A large perennial plant of the Polygonaceae family. Native to the Sichuan, Qinghai, and Tibet regions of China. It can reach a height of 2m. The rhizome is yellow and thick. From this rhizome grow large basal leaves with long stalks, which are egg-shaped and heart-shaped and several tens of centimeters long. In early summer, a magnificent panicle blooms at the top of the stem, bearing numerous small green-yellow flowers. The swollen rhizome has long been called daio and has been used medicinally as a laxative and stomach tonic. The closely related R. undulatum , native to northeastern China and Mongolia, has long been cultivated in Nara Prefecture for the same purpose, but has inferior medicinal properties.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

タデ科の大型多年草。中国の四川，青海，チベット地方原産。高さ 2mに達する。根茎は黄色で太い。この根茎から長い柄のある大きな根生葉を生じ，葉は長さ数十 cmの卵状心臓形である。初夏，茎の頂部に壮大な円錐花序を出し，多数の緑黄色の小花をつける。肥大した根茎を昔から大黄と呼び緩下剤や健胃剤などの薬用にした。近縁のカラダイオウ R. undulatumは中国東北やモンゴルの原産で，古くから同様の目的で奈良県下に栽培されているが，薬効は劣る。

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