Blue flag

Blue Flag a medicinal herb in full flower

Iris versicolor – Blue Flag

Other names : iris, liver lily, poison lily, flag lily, fleur-de-lys

Family: Iridaceae (Iris Family)

Habitat : Eastern and Central North America, growing in marshy places, producing distinctive blue flowers in spring. Commonly grown in Britain as an ornamental.

hazardsmallMany plants in this genus; the iridaceae, are thought to be poisonous if ingested, so caution is advised. The roots are especially likely to be toxic. Plants can cause skin irritations and allergies in some people. Fresh root can cause nausea and vomiting. The volatile oil furfural is irritant to mucous membranes and causes larchrymation (tears) and inflammation of the eyes. Irritation of the throat and headache also reported. The sap can cause dermatitis. Should not be used internally except in small doses. Should not be used by people with allergies or sensitivities .

OLYMPUS DIGITAL CAMERABlue Flag description:

Iris versicolor, Blue Flag, is a PERENNIAL growing to 0.6 m (2ft) by 1 m (3ft 3in).  It is hardy to zone 5. It is in flower from May to June. The flowers are hermaphrodite (have both male and female organs) and are pollinated by Insects.The plant is self-fertile. 

Suitable for: light (sandy) and medium (loamy) soils. Suitable pH: acid, neutral and basic (alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist or wet soil.

Blue Flag Cultivation :

Blue Flag prefers growing in marshy conditions. Very easily grown in any damp soil. Prefers a heavy rich moist soil and partial shade. Prefers a sunny position. Plants are hardy to about -25°c. This species has been cultivated by the N. American Indians as a medicinal plant. Members of this genus are rarely if ever troubled by browsing deer or rabbits.

Collection : The rhizome is best collected in the autumn.

Iris_versicolor_botanicalMedicinal uses of Blue Flag:

Actions : Cholagogue, hepatic, alterative, laxative, diuretic, anti-inflammatory.

Part Used : Rhizome

Indications :

This useful remedy has a wide application in the treatment of skin diseases, apparently aiding the skin by working through the liver, the main detoxifying organ of the body. It may be used in skin eruptions such as eczema and psoriasis, it is valuable as part of a wider treatment. It may be used with value where there is constipation associated with liver problems or biliousness.

Priest & Priest tell us that it is a “positive alterative for chronic, torpid conditions: influences glandular system, lymphatics, liver and gall ducts, and intestinal glands. Specific for hepatic congestion due to venous or lymphatic stasis.” They give the following specific indications : chronic hepatitis and rheumatic conditions, toxic sciatica(?). Scrophulous skin conditions, herpes, eczema, psoriasis. Enlarged thyroid gland. Uterine fibroids.

Ellingwood considered it specific for “clay-coloured stools, scanty urine and the skin inactive and jaundiced. In small doses it is indicated for irritable conditions of the mucous membranes of the digestive tract.” In addition he recommends it for the following pathologies : Chronic hepatic and intestinal disorders, chronic jaundice, bilious remittent fevers and chronic ague. Conditions of the stomach that induce sick headaches. Syphilis. Psoriasis, eczema, tinea. Goitre.

Kings Dispensatory says: “The specific indications for Iris may be stated as fullness of thyroid gland; enlarged spleen; chronic hepatic complaints with sharp, cutting pain, aggravated by motion; nausea and vomiting of sour liquids, or regurgitation of food, especially after eating rich pastry or fats; watery, burning bowel discharges; enlarged Iymphatics, soft and yielding; rough greasy conditions of the skin; disorders of sebaceous follicles; abnormal dermal pigmentation; menstrual wrongs, with thyroid fullness; unilateral fullness; unilateral facial neuralgia; muscular atrophy and other wastings of the tissues.”


Blue Flag combines well with Echinacea or Burdock and Yellow Dock.

Preparations & Dosage of Blue Flag :

Decoction: Put 1 teaspoonful of the dried herb into a cup of water and bring to the boil. Let it simmer for 10-15 minutes. This should be drunk three times a day.

Tincture: take 1 ml of the tincture three times a day.

Other uses of Blue Flag:

Litmus; Repellent; Weaving.

A fine blue infusion is obtained from the flowers and this can be used as a litmus substitute to test for acids and alkalis. The leaves have been used to weave baskets and mats. Some native North American Indian tribes used the root as a protection against rattlesnakes. It was believed that, so long as the root was handled occasionally to ensure the scent permeated the person and their clothes, rattlesnakes would not bite them. Some tribes even used to chew the root and then hold rattlesnakes with their teeth and were not bitten so long as the scent persisted.

iris_flower_fairy_mary_cicelyEsoteric uses of Blue Flag:

Gender: Feminine. Planet: Venus. Element: Water. Money. Carry the root for financial gain. Place in cash registers to increase business.

The Chemistry:
Constituents :
  • Volatile oil, containing furfural
  • Iridin (or irisin), a glycoside
  • Acids such as salicylic and isophthalic
  • Miscellaneous; a monocyclic C3l triterpenoid, gum, resin, sterols, etc.

  As is the case with most herbs there is still more research being done on Blue Flag and it’s uses we will keep you informed of any developments.

Further reading:

Iris versicolor

Iris versicolor, also commonly known as the Blue flag, Harlequin Blueflag, Larger Blue Flag, Northern Blue Flag and other variations of