Giant knotweed - Oitadori

Japanese: オオイタドリ - おおいたどり

A large perennial plant of the Polygonaceae family (APG classification: Polygonaceae). The stem is 1-3 meters tall, powdery white all over, and slightly arched. The leaves are ovate with sharp tips, 15-30 cm long, heart-shaped at the base, with short hairs along the veins on both sides, and the undersides are powdery white and thick and paper-like. The leaf sheaths are dry membrane-like. Dioecious. Flowering season is August-September, with panicles in the upper axils at the ends of the branches, and the inflorescences are densely hairy. The perianth is white. It grows in clusters in moist mountain valleys in Hokkaido and the Chubu region and north of Honshu, and is distributed in the Kuril Islands, Sakhalin, and Ulleung Island. It is similar to Japanese knotweed, but differs in that it is large, powdery white all over, and has heart-shaped leaves at the base.

[Junko Kobayashi December 11, 2020]

[Reference item] | Japanese knotweed

Giant Knotweed
It grows in clusters in the moist mountain valleys of the Chubu region and north, and produces panicles in the upper leaf axils at the ends of the branches from August to September. ©Shogakukan Photo by Okuyama Hisashi

Giant Knotweed

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

タデ科（APG分類：タデ科）の大形多年草。茎は高さ1～3メートル、全体に粉白を帯び、やや弓状に屈曲する。葉は卵形で先は鋭くとがり、長さ15～30センチメートル、基部は心臓形で両面葉脈に沿って短毛があり、裏面は著しく粉白を帯び、厚い洋紙質。葉鞘(ようしょう)は乾膜質。雌雄異株。花期は8～9月、枝先の上部葉腋(ようえき)に円錐(えんすい)花序をつけ、花序には密に毛がある。花被(かひ)は白色。北海道、本州の中部地方以北の山地谷間の湿り気の多い所に群生し、千島、樺太(からふと)（サハリン）、鬱陵島(うつりょうとう)に分布する。イタドリに似るが、全体に大形で粉白を帯び、葉の基部が心臓形であるなどの点で異なる。

［小林純子　2020年12月11日］

[参照項目] | イタドリ

オオイタドリ

出典　小学館　日本大百科全書(ニッポニカ)日本大百科全書(ニッポニカ)について　情報 | 凡例

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