Blue Flag Common names Parts used Uses Other medical uses Habitat and cultivation Constituents Usual dosage Side effects and cautions

Blue Flag

Iris versicolor

Herbs gallery - Blue Flag

Common names

  • Blue Flag
  • Blue Iris
  • Flag Lily
  • Fleur-de-lis
  • Flower de-luce
  • Iris
  • Liver Lily
  • Poison Flag
  • Snake Lily
  • Water Flag
  • Wild Iris
Blue flag (botanical name, Iris versicolor) is also known as wild iris and it prevails nearly all over the West. The appearance of blue flag is similar to that of the common iris, having elongated lance-shaped leaves and decorated with a pale lavender or bluish-purple bloom just a bit lesser in size compared to the garden varieties. In effect, blue flag is considered to be an affable plant which prefers to grow in clusters rather than growing in isolation. It is said that there is nothing more beautiful compared to walking across a complete meadow with blue flag in bloom during the period between late June and early July. The leaves of blue flag are slender, lance-shaped and have two levels of sword-shaped, elongated, slender leaves emerging from the dense upright rootstock (corm) that are smothered with fibrous roots. The root stock grows up to a height of four feet in expanding clusters. Each leaf is rather short compared to the whole herb. The leaves of blue flag are doubled/ creased along the midribs to enable it to take the shape of an overlying horizontal fan. The stems of blue flag are straight, not much above the ground and usually possess basal leaves which are over 1 cm in width. The plump stems emerge from a wide, tubular, crawling rootstock that gives rise to almost erect flowering stalks. The root or rhizome of blue flag has a propensity to develop into large clusters from wide, crawling rootstocks having annual joints that are about 2 inches or more in length and approximately 3/4 inch across. The rhizome has a tubular shape in the bottom half and gradually becomes compressed near the crown. Near the crown of the rhizome is a stem scar in the shape of a cup. When the rhizome becomes dry, several rings appear on it. Blue flag rhizome has a deep brown hue outwardly and is wrinkled longitudinally. The crack in the rhizome is small, has a purple tinge, while the vascular bundles are distributed all through the central or main column. The rootlets are elongated, simple and thin. Blue flag derives its name from the Greek goddess of the rainbow and plants belonging to this genus bear flowers of many hues, which are among the most colourful blooms and since long they have remained a basis in permanent gardens. In effect, blue flag is among the various wild irises that are indigenous to the eastern region of North America. Blue flag was named thus by the early European settlers in North America owing to its very intimate similarity to an ordinary European species called the yellow flag that formed the model for the insignia of the French monarchs - fleur-de-lis. It may be noted that blue flag is also called the liver lily since the dried up and pulverized rhizomes of the herb were conventionally thought to be a wonderful medication for cleansing the contaminations of the blood as well as the different maladies of the liver. Blue flag has several other therapeutic uses in folk medicine and this includes treating skin disorders, rheumatism and also the sexually-transmitted disease (STD) known as syphilis. However, no other people have valued the therapeutic attributes of blue flag as the native Indians of North America. In face, many native Indians in North America consider the herb to be a cure-all (panacea). They employed the herb in the form of a poultice to heal sores and bruises and this aspect of the blue flag was not taken up by the White settlers in North America. It is said that some tribes in North America have grown blue flag close to their villages with a view to make certain that the supply of the herb is expedient.

Parts used

Root, rhizome.


Contemporary practitioners of herbal medicine primarily use blue flag to detoxify the body. The use of formulations prepared with blue flag enhances urine flow as well as production of bile. In addition, they also have a gentle laxative action. These combined properties of cleansing the body make blue flag a valuable remedy for persistent skin disorders, for instance acne and eczema, particularly wherein constipation or gallbladder problems are responsible for the skin problems. Blue flag is also recommended for treating biliousness (excessive bile secretion) and indigestion. When taken in small doses, blue flag provides relief from vomiting and nausea. Nevertheless, when taken in large doses, blue flag itself induces vomiting. Traditionally, blue flag has been used to treat chronic gland problems. In addition, many also consider blue flag to facilitate weight loss. Depending on the Native American practices, physicians of the 19th century who depended on herbs and were known as Eclectic physicians as well as herbalists employed blue flag to treat several medical conditions. It may be noted that when not used as a specific immune stimulator, blue flag was employed as a laxative as well as to detoxify the intestinal tract. Freshly obtained and chopped blue flag rhizomes are applied to sores of impetigo (a widespread bacterial skin contagion in children), which has been often recommended by herbalists. Conventional herbalists have employed blue flag to cure improper digestion marked by mal-absorption of fat. In earlier times, blue flag was amongst the most preferred medicinal plants among diverse Indian tribes in North America. Blue flag also has a gentle purgative action. People using this herb ought to be cautious while use. However, there are reports that this herb also has toxic effects. Freshly obtained rhizome of blue flag is fairly pungent and when it is taken internally it may result in purging and colic. However, the dried out root of the herb is far less caustic/ pungent. Blue flag should never be given to women during pregnancy. The rhizome of blue flag possesses anti-inflammatory, alternative, cholagogue (any medicine that promotes bile secretion), cathartic (any substance that acts as a purgative), diuretic, diaphoretic (any medical substance that induces sweating), and emetic as well as sialagogue (any medication that promotes flow of saliva) properties. When the root of blue flag is taken internally, it works as a potent laxative or emetic that also has a strong action on the liver and encourages secretion of surplus body fluids. The root is also a tonic for the circulatory as well as the lymphatic systems. As the rhizome of blue flag possesses detoxifying action, it is very effective in treating skin disorders, such as acne, psoriasis and herpes. This attribute of the herb also makes it an important remedy for swollen glands, arthritis, pelvic inflammatory ailment and so on. The root of blue flag is also applied externally to cure wounds and alleviate rheumatic joint pains. The rhizomes are gathered during the later part of summer or in early autumn and are generally dried up for use when necessary. Earlier, the roots of blue flag were boiled in water and subsequently smashed to prepare a poultice that was employed to alleviate the pain and swelling attributed to bruises and sores. A number of indigenous Indian tribes of North America employed blue flag roots in the form of protection against rattlesnakes. They were of the belief that as long as the root of the herb was handled from time to time to make certain that its aroma seeped into the individual as well as his/ her clothes, rattlesnakes would never bite them. A number of the native tribes also chewed the root of blue flag and subsequently held rattlesnakes with their teeth and were never bitten till the time the scent remained.

Other medical uses

Habitat and cultivation

Blue flag is indigenous to North America. This herb has a preference for swampy and boggy areas in the wild. Additionally, blue flag is also extensively grown as a garden plant. The rhizome of this herb is dug up during autumn.


Chemical analysis of the blue flag herb has revealed that it encloses isophthalic acids, salicylic acids and triterpenoids as well as a little quantity of a volatile oil, resin, starch, tannins and an oleo-resin. The resinous portion of blue flag encloses several phenolic glycosides. Conventional texts on herbs hint that these constituents in blue flag invigorate the parasympathetic nervous system resulting in the production of saliva, bile and sweat.

Usual dosage

Medicinally, blue flag is taken in the form of decoction and tincture. Decoction: To prepare a decoction, add half to one teaspoonful dried herb to a cup (250 ml) of water and boil the mixture. Allow the mixture to simmer for about 10 to 15 minutes and subsequently filter the liquid. For best results, you ought to drink the decoction thrice every day. Tincture: Blue flag tincture should be taken in dosage of 2 ml to 4 ml thrice every day.

Side effects and cautions

People using herbal formulations prepared with blue flag ought to be cautious while using them for this medication may result in vomiting, nausea and loose stools when taken in excessive doses. Hence, it is advisable not to surpass the dosage recommend by your doctor. The freshly obtained rhizome of blue flag ought to be solely applied externally and never ingested, as internal use of this part of the herb may result in irritation of the mouth. In addition, it may also result in diarrhea and nausea. It is essential to take blue flag only after consulting an herbalist or physician who is trained in the use of this herb. As blue flag has been found to be unsafe for use during pregnancy as well as by nursing mothers, they should never be given this herb. In addition, blue flag should also never be given to children.

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