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Acorus gramineus - Sol. ex Aiton.

Common Name Grass-leaved Sweet Rush, Japanese Sweet Flag, Dwarf Sweet Flag
Family Araceae
USDA hardiness 6-10
Known Hazards Although no records of toxicity have been seen, this species belongs to a family where most of the species are poisonous, at least in the fresh state. The following notes are from the related A. calamus - the fresh root can be poisonous[7]. When using the plant medicinally, the isolated essential oil should not be used[165].
Habitats Wet places by streams and around ponds in C. and S. Japan[58].
Range E. Asia - China, Japan, India.
Edibility Rating    (3 of 5)
Other Uses    (0 of 5)
Weed Potential No
Medicinal Rating    (3 of 5)
Fully Hardy Moist Soil Wet Soil Water Plants Full sun
Acorus gramineus Grass-leaved Sweet Rush, Japanese Sweet Flag, Dwarf Sweet Flag

Acorus gramineus Grass-leaved Sweet Rush, Japanese Sweet Flag, Dwarf Sweet Flag


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Bloom Color: Green. Main Bloom Time: Early summer, Late summer, Mid summer. Form: Rounded.

Physical Characteristics

 icon of manicon of flower
Acorus gramineus is an evergreen Perennial growing to 0.3 m (1ft) by 0.2 m (0ft 8in).
It is hardy to zone (UK) 5 and is not frost tender. It is in leaf all year, in flower from June to July, and the seeds ripen from July to August. The species is hermaphrodite (has both male and female organs) and is pollinated by Insects.
Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: acid, neutral and basic (alkaline) soils. It cannot grow in the shade. It prefers moist or wet soil and can grow in water.



 Ground Cover; Pond; Bog Garden;

Edible Uses

Edible Parts: Root.
Edible Uses: Condiment.

Root - raw or cooked[105, 177]. It should be peeled, finely chopped and soaked in several changes of water first[183]. A stronger and more pleasing taste than A. calamus[2, 183]. The root is also used as a ginger substitute[177]. Some caution is advised, see the notes above on toxicity.

Medicinal Uses

Plants For A Future can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.

Anodyne;  Antibacterial;  Antifungal;  Antiperiodic;  Antirheumatic;  Antispasmodic;  Aromatic;  Cardiac;  
Carminative;  Diaphoretic;  Diuretic;  Emmenagogue;  Expectorant;  Febrifuge;  Parasiticide;  
Sedative;  Stimulant;  Stomachic;  Tonic;  Vermifuge.

The root is antifungal, antibacterial, antiperiodic, antirheumatic, antispasmodic, aromatic, cardiac, carminative, diaphoretic, emmenaggue, febrifuge, sedative, stimulant, stomachic, tonic and vermifuge[4, 7, 9, 21, 61, 147, 165, 176, 178, 218, 238, 240, 279]. It is also powdered and applied to bleeding gums[218, 238]. It is used internally in the treatment of digestive problems - particularly gastralgia and diarrhoea[283], cough, bronchial asthma, neurasthenia, depression, epilepsy etc[176, 238, 283]. Externally, it is used to treat body parasites, dermatosis and haemorrhoids[283]. The root can be harvested at any time of the year, except when the plant is in flower[238]. The root contains an essential oil consisting of asarone and asaryl aldehyde, plus a bitter glucoside acorin[176, 283]. Asarone increases the hypnotic effect of barbiturates and ethanol, lowers blood pressure and is antibacterial against Staphylococcus aureus, streptococci and mycobacterium[176]. The whole plant is anodyne, antiperiodic, antispasmodic, digestive, diaphoretic, diuretic, expectorant, sedative, stimulant, stomachic, sudorific, tonic, vermifuge[218].

Other Uses

Essential;  Insecticide;  Parasiticide;  Repellent.

The dried root repels insects[178]. It is probably also insecticidal[178, 240] and is used in Vietnam to kill lice, bugs and fleas[283]. An essential oil is obtained from the plant[240]. A useful ground cover plant, forming a spreading clump[208].

Cultivation details

Landscape Uses:Container, Foundation, Ground cover, Massing, Rock garden, Seashore. Grows well in shallow water margins of ponds etc[1, 2], though it can also succeeds in drier habitats[56]. Requires a sunny position[200]. A very ornamental plant, there are some named varieties[208, 238]. The cultivar 'Pusillus' can be grown as a submerged aquatic plant[238]. Special Features:Attractive foliage, Fragrant foliage, Not North American native, Naturalizing, Wetlands plant, Inconspicuous flowers or blooms.


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Seed - best sown in a cold frame as soon as it is ripe. Stand the pot in about 3cm of water. Pot up young seedlings as soon as they are large enough to handle, keep them wet by standing the pots in shallow water and overwinter for the first year in a greenhouse or cold frame. Division in spring just before growth starts[1]. Very easy, the plants can be divided at any time in the growing season and can be planted direct into their permanent positions[K].

Other Names

If available other names are mentioned here

Found In

Countries where the plant has been found are listed here if the information is available

Weed Potential

Right plant wrong place. We are currently updating this section. Please note that a plant may be invasive in one area but may not in your area so it’s worth checking.

Conservation Status

IUCN Red List of Threatened Plants Status :

Related Plants
Latin NameCommon NameEdibility RatingMedicinal Rating
Acorus calamusSweet Flag - Calamus34
Iris pseudacorusYellow Flag, Paleyellow iris12


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Sol. ex Aiton.

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Subject : Acorus gramineus  
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