Acorus is a genus of monocot flowering plants. This genus was once placed within the family Araceae (arums), but more recent phylogenies place it in its own family, Acoraceae, and order, Acorales.

The name 'Acorus' is derived from the Greek word 'acoron', name used by Dioscorides, which in turn was derived from 'coreon", meaning 'pupil', because the herb was used against inflammation of the eye.

These plants occur in North America or Asia. They were introduced in the 16th century in most countries of Europe.

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.

Sweet Flag - leaves

The inconspicuous flowers are arranged on a lateral spadix (a thickened, fleshy axis). Contrary to the arums, there is no spathe (large bract, enclosing the spadix). The spadix is 4 to 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 leaves and the rhizomes give a sweet scent when dried. Fine-cut leaves used to be strewn across the floor. In the Middle Ages it was used against the pest.

Species

The genus includes only two species:

• Acorus calamus (Calamus or Sweet Flag)
  • Acorus calamus var. americanus : occurrung in subarctic America to North and East USA
  • Acoris calamus var. angustatus : occurring in Asia.
  • Acoris calamus var. calamus : occurring in Himalaya, Siberia to Korea.
• Acorus gramineus (Japanese Sweet Flag or Grassy-leaved Sweet Flag); occurring in the Himalayas to Japan, Myanmar, Thailand, the Philippines.

Sweet Flag (drawing)

Reference

Govaerts, R. & Frodin, D.G. (2002). World Checklist and Bibliography of Araceae (and Acoraceae). 1-560. The Board of Trustees of the Royal Botanic Gardens, Kew.

External links

Section Miscellaneous information

• Sweet Flag (http://www.killerplants.com/weird-plants/20020516.asp) how various species arrived in America @ killerplants.com

Section Eclectic herbal information

• Acorus calamus (Sweet Flag) (http://www.ibiblio.org/herbmed/eclectic/kings/acorus.html) King's American Dispensatory @ Henriette's Herbal
• Sedge, Sweet (http://www.botanical.com/botanical/mgmh/s/sedges39.html) Mrs. Grieve's "A Modern Herbal" @ Botanical.com