In a cool and flowing clear stream, a waterborne flower blooms resembling plum blossoms, known as “Baikamo”. It bears white flowers resembling plum blossoms from early summer to early autumn. Baikamo is a native species of Japan and thrives in cool waters, hence it is widely distributed in waterways and rivers in northern Japan. However, in western Japan, it is confined to areas with upstream or spring water. It does not grow in stagnant waters; instead, its stems can reach almost 2 meters in length along the clear streams. The optimal temperature for its growth is around 15°C, and it withers if the temperature exceeds 25°C.
The photographed Baikamo is found in the Jizogawa River in Samegai, Maibara City, Shiga Prefecture. Samegai is the 63rd post town on the Nakasenndo Road, an inland highway that stretches 534km between Tokyo Nihonbashi and Kyoto Sanjo Ohashi. Samegai has been depicted in ukiyo-e prints by the artist Hiroshige Utagawa and was already renowned for its pure waters from the Isame no Shimizu spring and the waterborne flower “Baikamo” blooming in the Jizogawa River.

冷涼で流れのある清流中に生育し、初夏から初秋にかけてウメの花のような白い花を水中につける水中花、その名を梅花藻(ばいかも)といいます。日本の固有種で、冷水を好むため、北日本では水路や河川などに広く分布しますが、西日本などでは上流や湧き水のある地域に分布域が限られています。静水では育たず、清流に沿って茎の長さは2m近くにもなり、生育適温は15℃で、25℃を超えると枯れてしまいます。写真の梅花藻は滋賀県米原市醒井の地蔵川に咲いているものです。醒井は旧中山道(東京日本橋から京都三条大橋を結ぶ全長534kmの内陸街道)の63番目の宿場町で歌川広重の浮世絵にも描かれていて、居醒の清水（いさめのしみず）から湧き出る清流、地蔵川に咲く水中花「梅花藻（ばいかも）」は当時から有名でした。