Water lily - Water lily

A perennial aquatic plant in the family Plantaginaceae (APG classification: Plantaginaceae). The submerged leaves are thin lanceolate, and the above-water leaves are triangular or kidney-shaped. From July to September, the flower stalk emerges from the leaf axil above the water surface, and pale pink bisexual flowers bloom. Many closed flowers are produced underwater. The corolla is tubular and bilaterally symmetrical, bulging at the top, with five lobes at the tip and somewhat lip-shaped. There are four stamens, two of which become pseudo-stamens. The ovary is medium-sized and two-chambered, only one of which matures, and contains two drooping ovules. The fruit is cylindrical and closed, enclosed in a calyx tube with 3 to 5 thorns, and contains one seed. It grows in hilly ponds and marshes, and is distributed from Honshu to Kyushu, as well as the Korean Peninsula and China. The name comes from the fact that the leaves and fruits resemble those of water chestnuts (family: water chestnut).

The family Trapelaceae consists of only Trapelacea, with one genus and one species.

[Hideo Takahashi August 20, 2021]

In the APG classification, it is included in the Plantaginaceae family, and the Family Pycnonotidae has disappeared.

[Editorial Department, August 20, 2021]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

ヒシモドキ科（APG分類：オオバコ科）の多年生水草。水中葉は細い披針(ひしん)形、水上葉は三角状円形または腎臓(じんぞう)状円形。7～9月、葉腋(ようえき)から花柄を水面上に出し、淡紅色の両性花を開く。水中には多くの閉鎖花をつける。花冠は筒形で左右相称、上方は膨らみ、先は5裂し、やや唇形となる。雄しべは4本、2本は仮雄蕊(かゆうずい)となる。子房は中位で2室、1室のみが成熟し、胚珠(はいしゅ)が2個垂れ下がる。果実は円柱形の閉果で、3～5本の刺(とげ)のある萼筒(がくとう)に包まれ、1個の種子がある。丘陵の池沼に生え、本州から九州、および朝鮮半島、中国に分布する。名は、葉や果実がヒシ（ヒシ科）に似ることによる。

　ヒシモドキ科Trapellaceaeはヒシモドキのみからなり、1属1種である。

［高橋秀男　2021年8月20日］

　APG分類ではオオバコ科に含められ、ヒシモドキ科は消滅した。

［編集部　2021年8月20日］

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