Acorus gramineus commonly known as Dwarf Sedge, Japanese Rush or Japanese Sweet Flag, is a species belonging to the genus Acorus from, Acoraceae family. It is native to Japan and Korea, usually grows in wetlands and shallow water.

Dwarf Sedge is a perennial, shrubby plant with narrow, slightly curved leaves. It may grow up to 40 cm in height. It grows in a dense clump or tuft rising from a slender rhizome that lies just below the surface of the potting mixture.

Acorus gramineus can grow fully or partially submerged, or in very moist soil. It will flower when at least partially submerged, prefers full sun to part shade. As a marsh plant, Dwarf Sedge needs more water than most other types of plants. These plants must never be allowed to dry out at the roots. Scorched leaf tips will occur if soils are allowed to dry out. When grown in hot summer climates appreciate some relief from hot summer sun. Slowly naturalizes by spreading roots, but is not too aggressive. Propagation may be done easily by separating overcrowded clumps in spring or summer.Plant may stand -25°C.

There are many varieties: Acorus gramineus ‘variegatus’ has white stripes on its green leaves. Acorus gramineus ‘albovariegatus’ is a variegated and dwarf form. Acorus gramineus ‘Ogon’Golden Dwarf Acorus is a dwarf cultivar to 25 cm tall. It has linear fans of glossy, pale green and cream-striped leaves that have an overall golden effect.

Use in Landscape: Dwarf Sedge can be used as groundcover in small areas of water gardens, along streams or ponds or in moist open woodland gardens. Acorus gramineus spreads aggressively by rhizome, creating a nearly-seamless groundcover where conditions are favourable.

As it is a marsh plant, suited to aqua-terrariums and garden ponds, as well as submerged in freshwater aquaria. It also makes a useful aquarium plant but is short-lived where water temperatures exceed 22°C for long periods.