Isatis tinctoria

Isatis tinctoria

The dyer’s woad (Isatis tinctoria L.) is a biennial herbaceous species belonging to the Brassicaceae family.

Systematics –
From the systematic point of view it belongs to the Eukaryota Domain, Plantae Kingdom, Magnoliophyta Division, Magnoliopsida Class, Capparales Order, Brassicaceae Family and therefore to the Isatis Genus and I. tinctoria Species.

Etymology –
The term Isatis comes from ἰσάτις isátis, the classical Greek name of the dyer’s woad in Dioscorides and Hippocrates (from ἰσάζω isázo equalize, smooth): due to the abrasive properties of some plants of this genus.
The specific epithet tinctoria comes from tíngo dye: then used to dye fabrics.

Geographical Distribution and Habitat –
The woad is a plant of Asian origin that almost certainly was introduced in Europe starting from the Neolithic.
Other authors claim that it was imported into Italy by the Cathars who settled in the Piedmont area corresponding to the current city of Chieri.
This thesis would be corroborated by the fact that in the triangle between Toulouse, Albi and Carcassonne, the cultivation of Isatis tinctoria developed in the duchy of Lauraguais, from which the “pastel blue” was obtained, extremely sought after in painting and in the textile industry; this activity gave particular prosperity to these areas, originally poor, so much so that since then they have become defined as the “town of Cuccagna” (from cocagne, the French name given to the blue dye cake as it was marketed).
Its Italian diffusion is in the areas of the Western and Maritime Alps (Valle d’Aosta, Piedmont and Liguria), in the Veneto region, even if limited to the area of ​​the province of Treviso, in some regions of central-northern Italy such as Tuscany, Umbria and Marche and in central and southern Italy like Abruzzo and Lazio; we also find it in Sicily and Sardinia.
Its habitat is that of the uncultivated, ruins, along the roadsides and on trampled soils, usually with basic reaction, but also on silica sands, from sea level to the subalpine belt (about 2.000 m. S.l.m.).

Description –
The dyer’s woad is a biennial herbaceous plant that can reach a height between 40 and 120 cm.
In its first year of life the plant remains in a vegetative phase in which it forms a rosette of leaves; in the second year there is the development of the flower stem which leads to the subsequent fructification. The entire plant is glaucous.
The leaves are lanceolate, with dimensions from 1.5 to 5.0 cm in length.
The inflorescence is made up of about twenty purple-blue stems bearing flowers (gathered in dense racemes in the form of a corymb) with elliptical sepals and yellow petals, of which only a few mature. The diameter of the head varies from 3.5 cm to 18 cm.
The anthesis is between May and July.

Cultivation –
Isatis tinctoria grows on well-drained and rich soils, loves light but can grow even in mid-shade; it is a plant of easy cultivation that is re-seeded on its own even if it does not like to exploit the same soil twice.
The leaves are harvested from the first year and 3-4 crops can follow the first. the first year forms a rosette with a fresh appearance and a large taproot; it takes 20 months to flower and from the second year with its yellow flower it can light up the whole garden.

Uses and Traditions –
The dyer’s woad is a plant that has always been known and appreciated for its dyeing properties related to the blue color.
He made the wealth of the city of Erfurt (in Thuringia), but already the ancient Egyptians, the Bretons and the Romans used it as a remedy and as a dye.
Evidence of its ancient use comes from India, the Middle East and North Africa, while in Europe it has its maximum diffusion only in the late Middle Ages. The reasons for this delay are due to the fact that color is also a cultural construction: in European Mediterranean societies, blue has covered a marginal symbolic role throughout antiquity and the Middle Ages, for the Romans it even has negative connotations as identified with the color of barbarians who used to color their bodies to frighten their enemies.
The dyer’s woad, as a dye, was in fact also used by the Britons to dye the face of the characteristic blue / blue color that made their appearance more terrible in battle; “Dyeing” something in the civilized world was tantamount to saying it was red. Only starting from the 12th century the blue undergoes a progressive enhancement, up to a total reversal of the perspective in the modern age: suddenly, the blue becomes beautiful.
The cultivation and trade of the dyer’s woad then began to assume a considerable economic importance, particularly in Thuringia and in the Occitan territories included between the cities of Toulouse, Carcassonne and Albi, so much so as to give rise to the expression pays de cocagne – land of the bonanza – to indicate a place of extraordinary abundance and prosperity: the coques or cocagnes were dyeing pasta breads ready for sale. Even in Italy, between the fourteenth and fifteenth centuries, the dyer’s woad is the basis of essential trade flows for the economic development of numerous districts. It is processed in Umbria (the name of the town Gualdo Tadino derives from this plant), in the Apennine areas of the northern Marche (Montefeltro, upper valley of the Metauro and of the Foglia, Massa Trabaria), in some Tuscan territories (Arezzo, Val Tiberina), Piedmontese and Ligurians, but also in other parts of the country. His blue pigment was used not only for the coloring of fabrics, in many artistic sectors, from the miniature of manuscripts to the decoration of terracotta, to the paintings of the great Renaissance artists: he was widely used, for example, in numerous paintings by Piero della Francesca, whose father was a wealthy merchant of San Sepolcro dyer’s woad.
Subsequently there was a decline of Isatis tinctoria around the sixteenth century when its blue was supplanted by the dye matter extracted from the Indigofera – hence the name “indigo” – a plant that showed distinctly higher yields, better color uniformity and greater ease of processing.
We must arrive at the beginning of the nineteenth century to witness a hint of recovery for the cultivation of Isatis tinctoria, when the block of commercial relations with England set by Napoleon, known as the Continental Block (1806), also interrupts the import routes indigo making it necessary to recover the techniques, now obsolete, of extracting the blue pigment from local plants. With an imperial decree, money prizes are banned for those who managed to find the best and most profitable methods for cultivating and processing dyer’s woad or to discover another plant from which to extract quality color comparable to that of the Indigofera delle Indie and the Americas.

So in the time window of the first decade of the century, agronomists and chemists are mobilized, who give different prints to manuals in both French and Italian. Among these Giuseppe Morina, correspondent member of the Royal Institute of encouragement for the natural sciences of Naples, which opens his scientific Memoirs around the dyer’s woad affirming to be “well known to him the wise care of the Royal Institute of Encouragement to promote in this Kingdom the manufacture of ‘indigo, so to exempt our nation from a tribute, which annually pays to foreigners for the purchase of such valuable article so necessary for the blue colors “.
The flourishing economy linked to this plant is then gradually supplanted when industrially produced, less expensive synthetic dyes with more consistent and more durable colors put the use of natural dyes out of the market (which, on the other hand, especially in the vast crops Indians, held up by a brutal exploitation of local labor by European colonizers). The molecular structure of indigo is determined in 1878, four years later the first chemical synthesis is carried out and in 1897 two German factories start the production of synthetic indigo on an industrial scale, put on sale at a lower price of two marks per kilo compared to the natural one. It is a pity that in exchange for cheapness and a perfect color, which does not always rhyme with beauty, synthetic dyes are also polluting and harmful, causing a large environmental impact in the production phase and leaving toxic residues on the tissues more and more frequent allergic reactions and contact dermatitis.
The toxicity and unsustainability of the use of synthetic dyes is now bringing back to a gradual rediscovery of this and other dyeing plants.
The woad is cultivated as a fundamental use for the extraction of the blue color, but in the past it was also used as a medicinal plant to cope with iron deficiencies and debilitating states, to stimulate the growth of children, to treat scurvy and other diseases and, due to its astringent and healing properties, as an external pack against dermatitis, sores and wounds. It can be used as a forage for animals, even if it has a bitter taste, but it is rarely used in human nutrition due to its difficult digestibility.
The dye is contained in the leaves produced in the first year of life of the plant, since the concentration is quite low, it is necessary to use abundant quantities, gathered in full ripeness. The cut does not damage the plant, which will make new leaves grow, allowing four or five collections per season, at a distance of about twenty days from each other. At the end of the summer the dyeing properties are decreasing, for this reason it was usually forbidden for the last harvest to be mixed with the previous ones and it was traditionally fixed a collection deadline, which some medieval statutes of central Italy indicate for September 29th.
The leaves of Isatis tinctoria contain two complex organic compounds (indacane glucoside and isatano B ester) which are not soluble in water; the coloring substance (indigotine) is therefore not directly available but must be obtained through a precise processing. The yield is not very high, considering that no more than one or two grams of color can be obtained from a kilo of leaves.
In the seventies and eighties, the historian of local stories Delio Bischi brought to light in the Apennine territory of Montefeltro several stone millstones with particular grooves, often readapted as crossbars, aedicules and other constructions, assuming a different use from that of the millstones for wheat and olives. It was in fact dyer’s woad millstones used in the ancient processing practices of this plant, which reduced fresh leaves to pulp. Already in this first phase of the production process there was no lack of those who were ready to intervene fraudulently for their own advantage: “some bad faith farmers throw sand under the millstone, claiming that this is necessary to prevent the adhesion of the pasta to the circumference, but the real purpose is to increase the weight of the pastel.
The pasta thus obtained was first left to rest for a couple of weeks on racks or on an inclined surface, giving rise to a first fermentation with the foresight to constantly check for any cracks in the surface, to be closed to avoid the proliferation of worms ; subsequently the pasta was modeled into loaves or balls (coccagne) which again, turning them often, were left to stay in airy and shaded places while inside them the fermentation process continued. The loaves were modeled thanks to the help of special wooden bowls, their weight and their dimensions were precisely regulated: “the perfect breads are known by breaking them, because inside they are always purplish and pass on a very grateful smell; while the others, and more those of the leaf picked up in wet weather, give earthy color and unpleasant smell ”. After a few weeks, having become very hard, they were delivered to the pulp. Here they were crumbled into water, urine and vinegar (or wine) and left to macerate for at least fifteen days. One can imagine that the smell emanating from dyer’s woad pulps was not the best and in fact several archival documents testify to how their location was most of the time located outside the city walls. At the end of maceration, the dyer’s woad pasta was dried and reduced to powder, then sold to dyers.
Medieval recipes for the extraction of the blue color from the dyer’s woad can be read in the manuscript 2861 of the University Library of Bologna. It is a small format code, consisting of 239 cards of 15 lines, initially kept at the San Salvatore convent in Bologna where he had returned after the Napoleonic requisitions, integrally transcribed for the first time by Mary P. Merrifield in the second volume of his Original treatises on the arts of painting (1849). Among the procedures proposed in the manuscript, for example, we find the following, thus translated by Francesca Muzio: “crush very thin dyer’s woad grass, make bullets like apples, then take for each pound of dyer’s woad two ounces of common salt, three ounces of live sulfur and an ounce of rock alum; then chop well together and mix with the grass. Put everything in a copper pot with very clean water and dilute it like a not too thick sauce; put on the bright fire, and leave it so that it becomes like pasta; then raise it over a table and spread it rather thin. Cut it with the knife as you like, put it to dry and the indigo will be made. ” Or, still, this other rather hasty recipe: “knead dyer’s woad flower together with urine and strong vinegar, make it a smudge and dry it in the sun. And if you lighten up, put more dyer’s woad flower on it so that it has a good color; then cut it into pieces, let it finish drying, and it will be done. ”
Subsequently with the arrival on the market of the Indigofera tinctoria a different process of extraction of the indigo pigment, ie by oxygenation, is developed. This procedure is also extended to the dyer’s woad and it is the one that still continues to be tested and developed, with many different variants. In a nutshell, the process starts with the maceration of the fresh leaves in hot water, followed by the filtering and addition of a strong base (lye, slaked lime or caustic soda) to raise the pH. Oxygenation should also be encouraged, even simply by stirring everything vigorously and several times, in this way the indacano contained in the leaves oxidizes giving rise to the indigo which, not being soluble, falls to the bottom of the container. In the ancient maceri it was usually used a system formed by vats placed at different levels, in order to carry out the various operations taking advantage of the fall of the liquid, from the maceration tank, to the beater, to the restroom. Subsequently it passes to the drying in the air or the heat of a stove, then to the collection of the color in solid form. A final step consists in storing the so obtained breads in closed barrels, for about three weeks, so that they can exude excess moisture; after further drying the blue is definitely ready: “sell as quickly as possible – the manuals suggest – where you do not want to submit to a tare of a tenth or even more, which happens to the pasta in the first six months after done” .

The color then passed into the hands of the dyers. The techniques of the ancient dyeing procedures, despite their economic and social importance, have remained known only in an approximate way through indirect evidence, such as the accounting books in which quantity and quality of the ingredients used were recorded or the most important Arti medieval statutes ( The art of wool and silk) which controlled the dyeing activity by adjusting it to one’s own needs, therefore, these documents handed down “everything the dyer did not have to do; but more rarely what the dyer should have done; never, or almost never, how it would have worked in practice ”.
The solidity of the color extracted from this plant is proven by the medieval tapestries that have come down to us: the greens of the Bayeux Tapestry have been dyed with dyer’s woad surmounted on the yellow of the minor broom and the blues of the Apocalypse Tapestry have exceeded the centuries.
The dyer’s woad was one of the indigo dyes used, at one time, for dyeing the canvas with which blue jeans trousers were made. Blue jeans, thanks to the fibers from which they are made, are very resistant and were used as a uniform for workers who rubbed on the floor and needed a resistant dress.
As for the edibility, the leaves require a long soak to be used, as they are very bitter and keep a bit of a bitter taste even after boiling. The seeds, even if not edible, contain up to 34% protein and 38% fat.
In reference to its therapeutic value, for internal use the plant has a very astringent effect, it is used externally as a mash or poultice to heal ulcers, inflammation and stop bleeding. The leaves have antibacterial, antiviral, anticancer, astringent and febrifuge properties. The leaves are harvested in the summer and can be used fresh or dried, they are also macerated to extract the blue pigment useful for convulsions, mumps and fevers in children. The root as the whole plant is antibacterial and anticancer.
Today this plant, although almost completely replaced by Indigo (Indigofera tinctoria) and synthetic dyes, is still used to improve the yields of greens, blues and blacks. The oil contained in the seeds is used in cosmetics; with the plant extract the woods can be treated in order to preserve them better.

Preparation Mode –
Today it is possible to buy the blue pigment extracted from the plant by specialized artisans and dye the fabrics by preparing a “color bath” of warm water (55 ° C) with the addition of soda and sodium hydrosulphite.
The dye is extracted from the leaves of this plant collected during the first year of life. After maceration and fermentation in water, a yellow-green solution is obtained which agitates and oxidizes to produce a precipitate (indigotine). The dye, very solid, can be used in the dyeing of wool, silk, cotton, linen and jute, but also in cosmetics and pictorial colors.

Guido Bissanti

– Acta Plantarum – Flora of the Italian Regions.
– Wikipedia, the free encyclopedia.
– Treben M., 2000. Health from the Pharmacy of the Lord, Advice and experiences with medicinal herbs, Ennsthaler Editore
– Pignatti S., 1982. Flora of Italy, Edagricole, Bologna.
– Conti F., Abbate G., Alessandrini A., Blasi C. (edited by), 2005. An annotated checklist of the Italian vascular flora, Palombi Editore.

Attention: Pharmaceutical applications and food uses are indicated for informational purposes only, do not in any way represent a medical prescription; therefore no responsibility is assumed for their use for curative, aesthetic or food purposes.

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