Medical Herbs Catalogue



Botanical Name: Ivatis tinctoria (LINN.)
Family: N.O. Cruciferae

Synonyms: (Anglo-Saxon) Wad.
(French) Guède.
(Italian) Guado.
(Spanish and French) Pastel.
(Dutch) Weat.
Part Used: Leaves.

Dyer's Woad, French Guède (supposed to be derived from Gaudum, now Gualdo, the name of a town in the Roman States, where it was extensively cultivated), was formerly much cultivated in Britain for the dye extracted from the leaves. It is now nearly superseded by indigo, but is still cultivated in the south of France and in Flanders, as its dye is said to improve the quality and colour of indigo, when mixed in certain proportions. Woad is cultivated to a small extent in Lincolnshire and Woad mills are still worked at Wisbech, but not for the dye itself, the produce fixes true indigo, and is also used to form a base, or mordant, for a black dye.

Woad belongs to a genus spread over Southern Europe and Western Asia, and from having been much cultivated in many parts of Asia and Europe, has become established in stony and waste places as far north as Sweden. It is found in many parts of Great Britain, but not fully naturalized, except near Tewkesbury, where, according to Hooker, it appears to be indigenous. At the earliest time in the history of Britain it must have been plentiful in the country, since Caesar found the natives stained with it, but afterwards, probably from its extensive use, it became less common, and we find our Saxon forefathers importing Woad to dye their home-spun cloth. Their name for it was Wad or Waad, whence the English name woad.

Description: Gerard tells us: 'Glaston or Guadon, Woad is about three feet high, with long, bluish-green leaves growing round and out of the stalk, growing smaller as they reach the top, when they branch out with small yellow flowers, which in turn produce seed like little black tongues. The root is white and single. The Wild Woad is similar except that the stalk is softer, smaller and browner, and the leaves and tongues narrower. Where Woad is cultivated in fields, the wild Woad grows. It flowers from June to September. Caesar in his fifth book of the French wars mentions that the British stained themselves blue with woad. Pliny in his 22nd book, Chapter 1, says the French call it Glastum and British women and girls colouring themselves with it went naked to some of their sacrifices.

'Garden Woad is dry but not sharp, Wild Woad is drier and sharper and biting. The decoction made of Woad is good for hardness of the spleen, also good for wounds and ulcers to those of strong constitution and those accustomed to much physical labour and coarse fare. It is used as a dye, profitable to some, hurtful to many.' Culpepper says: 'Some people affirm the plant to be destructive to bees, and fluxes them, which if it be, I cannot help it. I should rather think, unless bees be contrary to other creatures, it possesses them with the contrary disease, the herb being exceeding dry and binding. . . . A plaister made thereof, and applied to the region of the spleen which lies on the left side, takes away the hardness and pains thereof. The ointment is excellently good for such ulcers as abound with moisture, and takes away the corroding and fretting humours: It cools inflammations, quenches St. Anthony's fire, and stays defluxion of the blood to any part of the body.' He also says that the seeds, if chewed, turn the saliva blue.

Cultivation: The cultivation of Woad was formerly carried on by people who devoted themselves entirely to it, and as crops of the plant are not successful for more than two years on the same piece of land, they never stayed long in one place, but hiring land in various districts, led a wandering life with their families and gained their living by their crops. Later, many farmers devoted a portion of their land to the growth of Woad, alternating the spots year after year.

Good loam soil is needed, land in good heart, repeatedly ploughed and harrowed from autumn till the following August, when the seeds are sown in drills, being thinned out by hoeing when about a fortnight old, to a distance of about 6 inches apart. In the spring, careful hoeing to remove weeds is necessary. The first crop can be gathered as soon as the leaves are fully grown, while perfectly green. The leaves are picked off when the plant is coming into flower. If the land be good and the crop well husbanded, it will produce three or more gatherings, repeated at intervals of a few weeks, but the first two gatherings are the best. An acre of land will produce a ton of Woad, and in good seasons, a ton and a half. If the land in which the seed is sown should have been in culture before for other crops, it will require dressing before it is sown - about twenty loads of stable manure to the acre being laid on and ploughed in with the last ploughing before the seeds are sown, this being enough to keep the ground in heart till the final crop of Woad is gathered.

Treatment of the Crop: The leaves are dried a little in the sun, then ground in a mill to a pasty mass, which is formed into heaps exposed to the air but protected from rain, until it ferments. A crust which forms over it is carefully prevented from breaking, and when fermentation is complete, usually in about a fortnight, the mass is again mixed up and formed into cakes. Before being used by the dyer, these cakes have to be again broken up, moistened and subjected to further fermentation. Much of the quality of the dye is said to depend on the way in which this operation is performed.

The colour is brought out by mixing an infusion of the Woad thus prepared with limewater.

The best Woad used to be worth L. (Lear) 20 or more a ton, till its price declined on the introduction of indigo, to which it is inferior in richness of colour, but is more permanent.

It is stated, also, that Woad leaves, covered with boiling water, weighted down for half an hour and the water poured off, treated with caustic potash and subsequently with hydrochloric acid, yield a good indigo dye. If the time of infusion be increased, greens and browns are obtained.

How the Ancients prepared the blue dye is not known.

Medicinal Action and Uses: The herb is so astringent, that it is not fit to be given internally as a medicine, and has only been used medicinally as a plaster, applied to the region of the spleen, and as an ointment for ulcers, inflammation and to stanch bleeding.

Ivatis indigotica is cultivated as a tinctorial plant in the north of China, where it is called Tein-ching. It is a small, halfshrubby plant, with a decumbent stem, bearing at its extremity several long drooping racemes of small yellow flowers, and smooth black fiddle-shaped pods about 1/2 inch long. The lower leaves are rather fleshy, on long stalks, oval, lance-shaped, and pointed, with the edges slightly toothed, the upper ones very much narrower and smaller. In the north of China, this plant takes the place of the indigo of the south, and its colouring matter is obtained by a process closely analogous to that employed in the preparation of indigo, but instead of being thoroughly inspissated so as to form solid cakes, it is used by the Chinese dyers in a semi-liquid or pasty state. It is commonly employed for dyeing cotton cloth, to which it imparts a dark-blue colour.