Aquatic Plant Encyclopedia

A Japanese aquatic plant that raises thick, arrow-shaped leaves above the water and bears yellow cup-shaped flowers in summer. Its name ('river bone') comes from the thick white rhizome. It has declined widely and is red-listed in many prefectures.

A Japanese native marsh plant that fans out narrow, sword-like leaves and forms colonies on rocky stream banks. Tough at the water's edge or in terrariums, but most forms decline when fully submerged; only dwarf cultivars cope under water.

A North American emergent plant (Japanese name Nagabamizuaoi) that holds glossy heart- to arrow-shaped leaves above the water and produces spikes of soft blue-violet flowers from June to October. Cold-hardy, it suits pond margins and large containers.

Japan's only native water lily, bearing small white flowers 3–7 cm across on the water surface, with red-purple leaf undersides. Its name refers to the 'hour of the sheep' (about 2 pm) when it is said to open. It has declined widely, so avoid wild-collected plants.

An aquatic plant that raises round, water-repellent leaves 40–50 cm across above the water and opens large white or pink flowers in summer. Its rhizome is the lotus root, and dwarf 'bowl lotus' cultivars can be grown in pots and jars.

A South American floating plant buoyed by swollen, bladder-like petioles, bearing pale violet flowers in summer. Extremely prolific and designated a Priority Control Alien Species in Japan, so it must never escape into outdoor waters.

The water lilies of the genus Nymphaea, with notched round leaves floating on the water and large flowers. They divide into cold-hardy temperate lilies and tropical lilies that hold blue or purple flowers above the water, with numerous hybrid cultivars.

A South American floating-leaved plant with round leaves that produces a succession of one-day, poppy-like yellow flowers. Called mizuhinageshi in Japanese. Cold-sensitive and listed as an alien species under consideration for control, so keep it out of the wild.

A creeping marsh plant (Japanese name Uchiwazenikusa) with round, shield-shaped leaves on slender stalks. A biotope staple, but naturalised in Japan and listed as a Priority Control Alien Species. It is distinct from the Specified Invasive Hydrocotyle ranunculoides.