Iwaichou - Iwaichou

A perennial plant of the Menyanthaceae family (APG classification: Menyanthaceae). Also known as ginkgo. It has a thick underground stem that grows horizontally, and the leaves are long-stalked, attached to the base of the plant, kidney-shaped, thick, shiny, and concave at the tip. The flower stalk is 15-40 cm tall. In July-August, the branch splits at the end of the flower stalk and white flowers open upward. The corolla is deeply divided into five lobes, the edges of the lobes are wavy, and there are long-stamen flowers and short-stamen flowers, depending on the species. It grows in clusters in the subalpine wetlands of Hokkaido and north of the Chubu region of Honshu, and is also distributed in northwestern North America. The name comes from the shape of the leaves, which resemble ginkgo. The genus Menyanthus consists of one genus and one species, and the type subspecies is distributed in North America.

[Hideo Takahashi November 17, 2021]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

ミツガシワ科（APG分類：ミツガシワ科）の多年草。別名ミズイチョウ。太い地下茎が横にはい、葉は長柄があって、根際につき、腎臓(じんぞう)形で厚く、光沢があり、先はへこむ。花茎は高さ15～40センチメートル。7～8月、花茎の先に枝を分け白色の花が上向きに開く。花冠は深く5裂し、裂片の縁(へり)は波打ち、長雄蕊花(ゆうずいか)と短雄蕊花があって株が異なる。本州の中部地方以北、北海道の亜高山帯の湿地に群生し、北アメリカ北西部にも分布。名は葉の形がイチョウを思わせるのでいう。イワイチョウ属は1属1種で、基準亜種は北アメリカに分布する。

［高橋秀男　2021年11月17日］

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