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Lesser Sweet Flag

Acorus gramineus

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Plant Profile

Flowering Months:
Acoraceae (Sweet Flag)
Also in this family:
Life Cycle:
Maximum Size:
60 centimetres tall
Water, wetland.

Green, 1 petal
A greenish-yellow spadix. Pollinated by insects.
A dry berry which is seldom produced in the British Isles. The seeds ripen in July and August.
Long, linear, sword-like leaves. Similar to Sweet Flag (Acorus calamus) but shorter and the leaves do not have a midrib.
Other Names:
Dwarf Sedge, Dwarf Sweet Flag, Grass-leaf Sweet Flag, Grass-leaved Sweet Rush, Grassy-leaved Sweet Flag, Japanese Rush, Japanese Sweet Flag.
Frequency (UK):
Rarely seen  

Similar Species

Other Information


Acorus gramineus, also known as grassy-leaved sweet flag or Japanese sweet flag, is a perennial wetland plant in the family Acoraceae. It is native to Asia, specifically China, Japan, and Korea, but it is now cultivated and naturalized in other parts of the world.

Acorus gramineus is a herbaceous perennial that can grow to about 1-2 feet tall. It has long, narrow, green leaves that are about 8-12 inches long, and are arranged in a fan-like fashion. The leaves are similar in appearance to those of a grass, which is why it is commonly called grassy-leaved sweet flag. The plant has a characteristic sweet aroma, which is particularly strong when the leaves are crushed. The flowers are small, greenish-white and are arranged in a dense spike. They appear in late spring or early summer.

Like Acorus calamus, A. gramineus has also been used in traditional medicine for its supposed medicinal properties. It is believed to have anti-inflammatory and antimicrobial properties, and the rhizomes of the plant have been used to treat a wide range of conditions, including digestive disorders, headaches, and respiratory infections.

However, just like Acorus calamus, the efficacy and safety of the plant have not been extensively studied or confirmed by modern scientific research. Additionally, this plant also contains small amounts of asarone, a chemical that in large doses can cause adverse effects such as hallucinations, seizures, and liver damage. Therefore, it is important to use the plant only under the guidance of a qualified healthcare practitioner.

Acorus gramineus is also commonly used as an ornamental plant, grown for its attractive, grass-like foliage and sweet aroma. It is adaptable to different growing conditions and can be grown in both aquatic and terrestrial settings. It is hardy to USDA zones 6-9. It is also propagated by rhizomes, which can be planted directly into the soil.


Lesser Sweet Flag (Acorus gramineus) is a perennial plant belonging to the family Acoraceae, and is native to Asia. It is commonly known as Japanese sweet flag, grass-leaved sweet flag, or dwarf sweet flag. The plant is often cultivated for its ornamental value and has a long history of use in traditional medicine.

Physical characteristics

Lesser sweet flag is a small, herbaceous plant that typically grows up to 30cm in height. The leaves are long and narrow, measuring up to 15cm in length and 1cm in width. The plant produces small, insignificant flowers on a spike that emerges from the center of the plant. The flowers are greenish-yellow and have a pleasant aroma.

Medicinal uses

The medicinal properties of Lesser Sweet Flag have been known for centuries. In traditional medicine, it is used to treat a wide range of ailments, including digestive problems, respiratory issues, and fevers. It is also used as a sedative and a diuretic.

The plant contains several active compounds, including asarones, which are known to have antimicrobial and anti-inflammatory properties. Asarones have been shown to be effective against a range of bacteria, including Staphylococcus aureus and Pseudomonas aeruginosa.

Lesser Sweet Flag has also been shown to have a calming effect on the nervous system, which makes it useful in the treatment of anxiety and insomnia. The plant contains beta-sitosterol, which is a compound that has been shown to have a sedative effect.

Other uses

In addition to its medicinal properties, Lesser Sweet Flag is also used in aromatherapy. The essential oil of the plant has a pleasant, sweet aroma and is used to promote relaxation and reduce stress. It is also used in the manufacture of perfumes and cosmetics.

Lesser Sweet Flag is also cultivated for its ornamental value. The plant is commonly used in landscaping and is a popular choice for rock gardens and border plantings. It is also grown in pots and used as an indoor plant.

Growing conditions

Lesser Sweet Flag is a hardy plant that is easy to grow. It prefers moist, well-drained soil and partial shade. It can tolerate a wide range of soil types, including sandy and clay soils. The plant is resistant to pests and diseases and requires minimal maintenance.


Lesser Sweet Flag can be propagated from seeds or by dividing established clumps. The plant is a slow grower, and it may take several years for it to reach its full size. If propagating from seed, it's important to keep the soil moist and warm, as the seeds can take several weeks to germinate.

Culinary uses

The roots of Lesser Sweet Flag have a sweet, slightly spicy flavor and are sometimes used in cooking. They can be chopped and added to salads, soups, and stews, or pickled for use as a condiment.


While Lesser Sweet Flag is generally safe for use in traditional medicine, it should be used with caution. The plant contains asarones, which can be toxic in large amounts. It should not be used during pregnancy or by people with liver disease.

Cultural significance

Lesser Sweet Flag has a long history of use in traditional Asian medicine and is considered a sacred plant in Hinduism. In Hindu tradition, it is used in various religious ceremonies, and its roots are believed to have purifying properties.

Aromatic properties

The essential oil extracted from Lesser Sweet Flag is used in aromatherapy for its calming and relaxing properties. It has a sweet, earthy scent and is believed to help reduce stress and anxiety.

Garden design

Lesser Sweet Flag is a popular choice for garden design due to its compact size and low maintenance requirements. It can be used in rock gardens, as a border plant, or in container gardening. Its long, narrow leaves provide a striking contrast to other plants, and its sweet scent adds to its overall appeal.

Insect repellant

The scent of Lesser Sweet Flag is also believed to repel insects, making it a useful plant for use in natural pest control. Its roots are sometimes used in sachets to keep moths and other pests away from clothes and linens.

In conclusion, Lesser Sweet Flag is a versatile and fascinating plant with a range of uses and benefits. Its traditional medicinal uses, ornamental and aromatic properties, and potential as an insect repellant make it a valuable addition to any garden or herbal medicine cabinet. While care should be taken when using it in traditional medicine, this plant has a long history of safe use and is well worth considering for a variety of applications.