|Acorus subsp. var.||Sweet flag|
Acorus is a genus of monocot flowering plants. This genus was once placed within the family Araceae (aroids), but more recent classifications place it in its own family Acoraceae and order Acorales, of which it is the sole genus of the oldest surviving line of monocots. The exact relationship of Acorus to other monocots, however, is still debated by scientists. Some studies indicate that it is placed in a lineage (the order Alismatales), that also includes aroids (Araceae), Tofieldiaceae, and several families of aquatic monocots (e.g., Alismataceae, Posidoniaceae). Common names include Calamus and Sweet Flag. It is known as vasambu in Tamil language.
The name 'acorus' is derived from the Greek word 'acoron', a name used by Dioscorides, which in turn was derived from 'coreon', meaning 'pupil', because it was used in herbal medicine as a treatment for inflammation of the eye.
The genus is native to North America and northern and eastern Asia, and naturalised in southern Asia and Europe from ancient cultivation. The known wild populations are diploid except for some tetraploids in eastern Asia, while the cultivated plants are sterile triploids, probably of hybrid origin between the diploid and tetraploid forms.
These grasslike evergreen plants are hemicryptophytes, (i.e. perennial plants of which the overwintering buds are at the soil surface) or geophytes (i.e. the overwintering buds are found underground, usually attached to a bulb, corm, tuber, etc.). Their natural habitat is at the waterside or close to marshes, often found with reedbeds.
The inconspicuous flowers are arranged on a lateral spadix (a thickened, fleshy axis). Unlike aroids, there is no spathe (large bract, enclosing the spadix). The spadix is 4-10 cm long and is enclosed by the foliage. The bract can be ten times longer than the spadix. The leaves are linear with entire margin.
The parallel-veined leaves of some species contain ethereal oils that give a sweet scent when dried. Fine-cut leaves used to be strewn across the floor in the Middle Ages, both for the scent, and for presumed efficacy against pests.
|Standard Cyclopedia of Horticulture|
Acorus (ancient name of unknown meaning). Araceae. Hardy, herbaceous water-loving plants. Lvs. sword-shaped, erect: spadix appearing lateral, with no true spathc; fls. inconspicuous. They thrive best in moist soil, and may be grown in shallow water or on dry land. Prop, easily in spring or autumn by division.CH
Pests and diseases
In older literature and on many websites, there is still much confusion, with the name Acorus calamus equally but wrongfully applied to Acorus americanus.
The genus includes as many as six species:
- Acorus americanus (Raf.) Raf. (formerly known as A. calamus var. americanus) - American Sweet Flag; fertile diploid (2n = 24); occurring in Alaska, Canada and northern USA. Diploid plants in Siberia and temperate Asia may also belong here, but have not been fully investigated (). Recently recognised as a distinct species by the Flora of North America.
- Acorus calamus L. - Common Sweet Flag; sterile triploid (3n = 36); probably of cultivated origin. It is native to Europe, temperate India and the Himalayas and southern Asia, widely cultivated and naturalised elsewhere.
- Acorus gramineus Sol. ex Aiton - Japanese Sweet Flag or Grassy-leaved Sweet Flag; fertile diploid (2n = 18); occurring in the Himalayas to Japan, Myanmar, Thailand, the Philippines.
- Acorus triqueter Turcz. ex Schott (syn. A. calamus var. angustatus) - fertile tetraploid (4n = 48); occurring in eastern Asia, Japan and Taiwan.
- Acorus latifolius Z.Y.Zhu : native to China
- Acorus xiangyeus Z.Y.Zhu : native to China