Acorus calamus

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 Acorus calamus subsp. var.  Common Sweet Flag, Calamus, Flagroot, Myrtle flag, Sweet calamus, Sweet flag
Acorus calamus1.jpg
Habit: herbaceous
Height: to
Width: to
4ft 3ft7ft
Height: warning.png"" cannot be used as a page name in this wiki. to 4 ft
Width: 3 ft to 7 ft
Lifespan: perennial
Poisonous: parts may be toxic
Bloom: early summer, mid summer, late summer
Exposure: sun, part-sun
Water: wet
Features: flowers, edible, foliage
Hidden fields, interally pass variables to right place
Minimum Temp: °Fwarning.png"°F" is not a number.
USDA Zones: 3 to 10
Sunset Zones:
Flower features: orange, yellow
Acoraceae > Acorus calamus var. , L.

Acorus calamus, commonly known as sweet flag or calamus and various rushes and sedges,[1] is a plant from the Acoraceae family, in the genus Acorus. It is a tall perennial wetland monocot with scented leaves and more strongly scented rhizomes, which have been used medicinally, for its odor, and as a psychotropic drug. Probably indigenous to India, Acorus calamus is now found across Europe, much of Asia, Australia, and southern Canada/Northern USA, where it may be mistaken for the native Acorus americanus.

The leaves are between 0.7 and 1.7 cm wide, with average of 1 cm. The sympodial leaf of Acorus calamus is somewhat shorter than the vegetative leaves. The margin is curly-edged or undulate. The spadix, at the time of expansion, can reach a length between 4.9 and 8.9 cm (longer than A. americanus). The flowers are longer too, between 3 and 4 mm. Acorus calamus is infertile and shows an abortive ovary with a shriveled appearance.

Standard Cyclopedia of Horticulture

Acorus calamus, Linn. Sweet Flag. Height 2 ft.: root- stock horizontal, pungent, aromatic: fls. early summer. N. Amer., Eu. Var. variegatus, Hort. Lvs. striped deep yellow when young, fading to a paler color later in summer. Eu.—Commoner in cult, than the type. CH

The above text is from the Standard Cyclopedia of Horticulture. It may be out of date, but still contains valuable and interesting information which can be incorporated into the remainder of the article. Click on "Collapse" in the header to hide this text.


It is hardy to zone 3 and is not frost tender. It is in flower from May to July, and the seeds ripen from July to August. The flowers are hermaphrodite (have both male and female organs) and are pollinated by Insects.

The plant prefers light (sandy), medium (loamy) and heavy (clay) soils. The plant prefers acid, neutral and basic (alkaline) soils. It cannot grow in the shade. It requires wet soil and can grow in water.

Prefers growing in shallow water or in a very moist loamy soil[200]. Requires a sunny position[200]. Prefers a pH in the range 5.5 to 7.5. Plants are hardy to about -25°c[187]. The sweet flag has a long history of use as a medicinal and culinary plant. It has been cultivated for this purpose but was more commonly allowed to naturalize and was then harvested from the wild. The plant seldom flowers or sets seed in Britain and never does so unless it is growing in water[4]. It can spread quite freely at the roots however and soon becomes established.


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. Seed is rarely produced in Britain[4, 17]. Division in spring just before growth starts[1]. Very easy, it can be carried out successfully at any time in the growing season and can be planted direct into its permanent positions[K].

Pests and diseases


One subspecies, Acorus calamus var. angustatus Besser, Synonyms: Acorus asiaticus, Acorus cochinchinensis, Acorus latifolius, Acorus rumphianus, Acorus spurius, Acorus triqueter, Acorus tatarinowii, Acorus terrestris, Orontium cochinchinense, Acorus calamus var. spurius, Acorus gramineus var. crassispadix.



  1. Other names include cinnamon sedge, flagroot, gladdon, myrtle flag, myrtle grass, myrtle sedge, sweet cane, sweet myrtle, sweet root, sweet rush, and sweet sedge

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