- Dyer’s Woad
A flowering plant, woad (botanical name Isatis tinctoria) belongs to the family Brassicaceae. The common name of this herb is dyer’s woad. In fact, the blue dye obtained from the plant’s leaves is also called woad.
Woad is a biennial herb that usually grows up to a height of anything between 50 cm and 100 cm. The plants are smooth and enveloped with purina. The root of this herb is fleshy and conical in shape, measuring about 2 cm to 3 cm across and about 20 cm to 30 cm in length. The main roots are yellow on the soil surface and have small stripes along with some petite fibrous roots. The basal leaves of woad appear in a rosette and the leaf blade varies from oblong to largely oblanceolate. They measure about 5 cm to 15 cm in length and 1.5 cm to 4 cm in width. The leaves have an obtuse apex and they may have wholly or partially wavy margins. The inflorescence is basically a raceme, either axillary or terminal. It forms a cone-like structure at the tip of the branch. Silicle or fruit of the plant is almost compressed, glabrous and comes with membranous wings on the sides. The woad fruit encloses a solitary seed, which is pale brown and oblong shaped. Generally, the flowers bloom between April and May, while the fruits are borne during the period between May and June.
Traditionally, woad is well-known for the blue dye extracted from its leaves. Since the time before the Roman invasion, Britons used this plant to extract the blue dye, which is obtained through a complex process involving fermentation of the leaves. An awfully bad smell is produced by the leaves during the drying and fermentation processes. However, the dye obtained from woad is seldom used these days, as it has been substituted by another tropical plant Indigofera tinctoria and very recently by synthetic products. All said and done, the blue dye extracted from woad leaves is of excellent quality and is still used by a section of artists and others who only wish to work with natural colors. This natural blue dye can be blended with dyer’s greenwood (scientific name Genista tinctoria) to produce a high quality green dye. In addition, people also use woad to enhance the quality of indigo and also to prepare a base for various types of black dyes.
People have cultivated woad since ancient times, mainly for its value as a dye plant. This herb was particularly cultivated in the western and southern regions of Europe. During the medieval period, several regions in England, France and Germany cultivated woad. Many European towns like Toulouse thrived well on woad trade. Eventually, the dye extracted from the plant was substituted by a more potent indigo. By the beginning of the 20th century, different types of synthetic indigos replaced woad as well as indigo.
In Traditional Chinese Medicine (TCM), woad has been used for several centuries and currently researchers are examining the possibility of using this herb to treat cancer. Earlier, this plant was used for craft purposes and currently this art has been revived to some extent.
How to extract the blue dye: The process of extracting the blue dye from woad involves harvesting the leaves from the flowering stems and drying them in the sun. Subsequently, the dried parts of the herb are pulverized and made into a paste. As the paste ferments, it emits a disgusting smell. The smell is so awful that during the reign of Tudor drying woad leaves near the royal palace was considered to be a serious offence. Then the fermented leaves are mixed with water and used to make cakes. These cakes are allowed to ferment again. The blue dye is extracted by permeating the fermented woad leaf cakes with lime water.
The traditional medical systems of Asia as well as Europe have been using woad (Isatis tinctoria) roots for more than 1,000 years now. Different ancient medical systems such as Ayurveda, Traditional Chinese Medicine (TCM), Unani and Siddha have been using Isatis tinctoria for treating a variety of health conditions including fever, oral sores, common colds, sore throat, mumps and even malignant tumours.
The root of woad possesses antibiotic properties and works to boost the immune system. This herb has been traditionally used for treating flu, fever, red and swollen face, tonsillitis, sore throat, herpes, hepatitis, a number of skin infections and chickenpox. Several herbal mixtures contain woad root and they can be employed for preparing herbal teas for treating flu and sore throat. The leaves of this herb also possess anti-inflammatory and antibiotic properties and they have been found to be effective in inhibiting the growth of cells of some cancer forms. In addition, woad leaves are also used for curing sore throat and fever, in addition to measles, meningitis, jaundice and specific hot skin rashes. The leaves of this herb can be used both topically as well as internally.
A plaster prepared from woad leaves can be applied to the skin over the spleen, which is found on the left side of the body, to alleviate pains and also to eliminate the stiffness of the organ. This plaster helps to pacify inflammations, reduces St. Anthony’s fire and prevents the deflecting of blood to any area of the body.
In Traditional Chinese Medicine (TCM), woad is extensively used internally. Often this herb is used in high doses with a view to preserve its active ingredients in elevated levels. The leaves of woad possess astringent, antiviral, antibacterial, anticancer and febrifuge properties. This herb is useful in checking a wide variety of microbes, including viruses. Woad leaves are used internally for treating an assortment of health issues counting influenza, encephalitis, erysipelas and others.
Woad leaves are collected during the summer months and you can use them fresh or dry and store them for later use. In addition the leaves of this herb are mashed to extract a blue pigment. The leaves are also used for treating spasms in children, in the form of a detoxifier to treat infectious conditions like mumps and cure coughing of blood. Woad root possesses antibacterial as well as anticancer properties and is also used for treating epidemic parotitis, macula associated with severe contagious diseases and pyogenic inflammation associated with meningitis and influenza.
In Traditional Chinese Medicine (TCM), woad is considered to be among the most effective herbal remedies. It is used as an herbal antiseptic, antibiotic and anti-viral. In addition, people who practice TCM employ this herb in almost all cases of toxic heat or fever caused by viral infections, scarlet fever, leukemia, blood poisoning, meningitis, mumps, tonsillitis, laryngitis, hepatitis and other similar health disorders. In effect, in a number of cases woad is an effectual alternative to the antibiotic used in the West. While the root of woad has widespread use, even the leaves of the plant are equally useful. According to TCM physicians, compared to the roots, the leaves of woad are more useful for treating health problems related to the upper part of the body. This is the main reason why they use the leaves of the plant along with its roots to treat various respiratory infections in the upper part of the body.
These days, the blue dye or pigment extracted from woad leaves is not in much use, as it was first replaced by a tropical plant called Indigofera tinctoria and later by synthetic products. However, this dye is of superior quality and is still used by a section of artists who wish to work only with natural dyes. When mixed with dyer’s greenwood (botanical name Genista tinctoria), this blue dye yields a superior quality green pigment. In addition, many people use the pigment from woad leaves to enhance the quality as well as color of indigo.
Habitat and cultivation
It is believed that woad (Isatis tinctoria) has its origin in the southern regions of Russia. Currently, having escaped from cultivation, this plant has naturalized in most regions of central as well as southern Europe. These days, woad can be found growing naturally in cornfields and cliffs. Most often it is found in chalky soils.
Woad can be propagated easily. This plant has a preference for fertile soil that is well-drained and a sunny location. However, woad also grows well in common garden soils and like soils that range from neutral to alkaline. Since woad exhausts nutrients from the soil on which it grows, the plant cannot be grown productively at the same site for over two consecutive years. When growing in favourable locations, woad self-sows easily as well as frequently. However, they will usually not thrive if they grow in the same place for over two years at a stretch.
Antibiotic properties: Studies undertaken to explore the health benefits offered by woad have shown that the plant has antibiotic effects. In vitro experiments involving a decoction prepared from the leaf of this herb have revealed that it possesses attributes that help to inhibit Streptococcus, Staphylococcus aureus, Streptococcus pneumonia, Neisseria meningitidis, Salmonella typhi, Shigella, Haemophilus influenza, catarrhal bacteria, diphtheria bacilli and E. coli.
In addition, woad leaf decoction also helps to inhibit mumps virus, encephalitis B virus and influenza virus. It also possesses the ability to eliminate leptospira.
Anti-endotoxin properties: In vitro tests involving the leaves of woad (Isatis tinctoria) have also confirmed their anti-endotoxin effects (contracting or inhibiting actions) on E. coli.
Chemical analysis of woad (Isatis tinctoria) leaf has shown that it contains a number of phytochemicals including indigotin or indigo, indirubin, and isatan B. In addition, it also contains vital inorganic elements like zinc, iron, copper, manganese, nickel, chromium, and the trace mineral selenium. The leaves of this herb also contain a chemical harmful for humans and called arsenic. When hydrolyzed, isatan can be converted into a compound called D-xylo-5-hexulofuranosonic acid and indigo.
Woad leaves offer a number of therapeutic benefits and, hence, have different applications. The standard dosage of the leaves differs depending on the manner in which they are taken. The starting dosage of a dried Isatis leaf powder and concentrated dried leaf decoction are given below:
Dried leaf powder: The starting dosage is taking two to three grams daily.
Dried leaf decoction extract: The starting dose is anything between one and four grams daily.
Side effects and cautions
Despite the health benefits offered by the plant, people who are already using anti-platelet or anti-coagulant drugs like Aspirin or Warfarin should use the woad roots with caution. In addition, people who are prone to allergic reactions following use of drugs containing sulfonamide, occasionally referred to as sulfa drugs, should also use the leaves and roots of this plant with caution.
Collection and harvesting
The leaves of woad (Isatis tinctoria) are generally collected when the plant has matured completely. A maximum of three to four harvests are possible in a year.