Onibasu - Onibasu

It is an annual aquatic plant of the Nymphaeaceae family (APG classification: Nymphaeaceae), and grows in ponds and marshes. Its Japanese name comes from its shape resembling that of a lotus and its many thorns. It is also called Mizubuki. It has a short cylindrical rhizome underground and produces many leaves. The leaves are attached to long, thorny petioles in a shield-like shape and float on the water surface. The leaf blade is circular, reaching a diameter of 20 cm to 3 m, is wrinkled, and has thorns on the veins. The underside is purple. It flowers from August to October, and there are two types of flowers: normal and closed flowers. The flower is a single terminal flower on a long, thorny stalk, about 4 cm in diameter. It has four green sepals, and numerous purple petals arranged in a spiral. It has many stamens. The ovary is divided into eight lobes at the lower part, and many ovules are attached to the inner wall of each lobe. The seeds are spherical and covered with arils. The endosperm of the seeds is rich in starch and is edible. In China, the seeds are called kenjitsu and are used as a tonic. There is only one species in one genus, and it is distributed in Honshu, Kyushu, Primorsky Krai of the Russian Federation, the Korean Peninsula, China, and India. In Japan, the number of plants has been rapidly decreasing recently due to pollution of ponds.

[Motomi Ito June 19, 2018]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

スイレン科（APG分類：スイレン科）の一年生の水草で、池や沼に生育する。和名は、形がハスに似ており、刺(とげ)が多いことによる。またミズブキともよばれる。地中に円筒形の短い根茎をもち、多数の葉を出す。葉は刺の多い長い葉柄に盾状につき、水面に浮かぶ。葉身は円形で径20センチメートルから3メートルにも達し、しわが多く、葉脈上には刺が生える。下面は紫色を帯びる。花期は8～10月、正常花と閉鎖花の2種の花がある。花は刺の多い長い花柄上に1個頂生し、径約4センチメートル。萼(がく)片は4枚で緑色、花弁は多数、紫色で螺旋(らせん)状につく。雄しべは多数ある。子房は下位で8室に分かれ、各室の内壁に多数の胚珠(はいしゅ)をつける。種子は球形で、仮種皮をかぶる。種子の胚乳はデンプンに富み、食用とされる。また、中国では種子を芡実(けんじつ)と称し、強壮剤としても利用する。1属1種で、本州、九州、ロシア連邦の沿海州、朝鮮半島、中国、インドに分布する。日本では最近、池の汚染などで急速に減っている。

［伊藤元巳　2018年6月19日］

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