Herb: Woad


Latin name: Isatis tinctoria


Synonyms: Isatis indigotica


Family: Cruciferae



Medicinal use of Woad:

Woad has rather a mixed press for its medicinal virtues. One author says it is so astringent that it is not fit to be used internally - it is only used externally as a plaster applied to the region of the spleen and as an ointment for ulcers, inflammation and to staunch bleeding. However, it is widely used internally in Chinese herbal medicine where high doses are often employed in order to maintain high levels of active ingredients. The leaves are antibacterial, anticancer, antiviral, astringent and febrifuge. It controls a wide range of pathogenic organisms, including viruses. It is used internally in the treatment of a wide range of disorders, including meningitis, encephalitis, mumps, influenza, erysipelas, heat rash etc. The leaves are harvested in the summer and can be used fresh or dried. They are also macerated and the blue pigment extracted. This is also used medicinally, particularly in the treatment of high fevers and convulsions in children, coughing of blood and as a detoxifier in infections such as mumps. The root is antibacterial and anticancer. It is used in the treatment of fevers, pyogenic inflammation in influenza and meningitis, macula in acute infectious diseases, erysipelas, mumps and epidemic parotitis. Its antibacterial action is effective against Bacillus subtilis, haemolytic streptococcus,, C. diphtheriae, E. coli, Bacillus typhi, B. paratyphi, Shigella dysenteriae, S. flexneri and Salmonella enteritidis. Both the leaves and the roots are used in the treatment of pneumonia. The root and the whole plant have anticancer properties whilst extracts of the plant have shown bactericidal properties.

Description of the plant:



Plant:
Biennial/Perennial


Height:
100 cm
(3 1/4 foot)

Flovering:
June to
August

Habitat of the herb:

Cliffs and cornfields, often on chalky soils.

Edible parts of Woad:

Leaves - they require long soaking in order to remove a bitterness, and even then they are still bitter. There is no record of the seeds being edible, but they contain 12 - 34% protein and 12 - 38% fat on a zero moisture basis.

Other uses of the herb:

Woad is historically famous as a dye plant, having been used as a body paint by the ancient Britons prior to the invasion of the Romans. A blue dye is obtained from the leaves by a complex process that involves fermenting the leaves and produces a foul stench. The dye is rarely used nowadays, having been replaced first by the tropical Indigofera tinctoria and more recently by synthetic substitutes. Nevertheless, it is a very good quality dye that still finds some use amongst artists etc who want to work with natural dyes. A very good quality green is obtained by mixing it with Dyer's greenwood (Genista tinctoria). Woad is also used to improve the colour and quality of indigo, as well as to form a base for black dyes. The leaves are harvested when fully grown and 3 - 4 harvests can be made in total. Recent research in Germany has shown that (the dyestuff in?) this plant is a very good preservative for wood.

Propagation of Woad:

Seed - sow spring in situ. Fresh seed can also be sown in situ in late summer, it will take 20 months to flower but will produce more leaves.

Cultivation of the herb:

Cliffs and cornfields, often on chalky soils.

Known hazards of Isatis tinctoria:

None known

Plant information taken from the Plants For A Future.