Isatis tinctoria

Taxonomy and growth

Family

Brassicaceae

Genus

Isatis

Life cycle

biennial, perennial

Height

1 m

Spread

0.45 m

Fertility

Insects

Flower type

hermaphrodite

Pollinators

Insects

Uses

Edible uses

This section contains historical Plants For A Future notes marked noncommercial.

Leaves - they require long soaking in order to remove a bitterness, and even then they are still bitter^[8][9]. There is no record of the seeds being edible, but they contain 12 - 34% protein and 12 - 38% fat on a zero moisture basis^[11].

Medicinal uses

Historical medicinal uses. These records describe reported uses. They do not establish safety or effectiveness. Ask a qualified health professional before using any plant medicinally.

This section contains historical Plants For A Future notes marked noncommercial.

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^[14]. 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^[12]. The leaves are antibacterial, anticancer, antiviral, astringent and febrifuge^{[4][7][11][12]}. It controls a wide range of pathogenic organisms, including viruses^[11][12]. It is used internally in the treatment of a wide range of disorders, including meningitis, encephalitis, mumps, influenza, erysipelas, heat rash etc^[12]. The leaves are harvested in the summer and can be used fresh or dried^[12]. 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^[12]. The root is antibacterial and anticancer^[7]. It is used in the treatment of fevers, pyogenic inflammation in influenza and meningitis, macula in acute infectious diseases, erysipelas, mumps and epidemic parotitis^[7]. 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^[7]. Both the leaves and the roots are used in the treatment of pneumonia^[11]. The root and the whole plant have anticancer properties whilst extracts of the plant have shown bactericidal properties^[11].

Material uses

This section contains historical Plants For A Future notes marked noncommercial.

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^[12]. A blue dye is obtained from the leaves by a complex process that involves fermenting the leaves and produces a foul stench^{[17][3][15][16][2][12]}. The dye is rarely used nowadays, having been replaced first by the tropical Indigofera tinctoria and more recently by synthetic substitutes^[12]. 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)^[12]. Woad is also used to improve the colour and quality of indigo, as well as to form a base for black dyes^[13]. The leaves are harvested when fully grown and 3 - 4 harvests can be made in total^[13]. Recent research in Germany has shown that (the dyestuff in?) this plant is a very good preservative for wood[Radio 4 Farming programme].

Environment

Range

C. and S. Europe. Naturalized in S. and C. England.

Habitat

Cliffs and cornfields, often on chalky soils^[6][10].

Light

full sun

Shade tolerance

light shade

Water

moderate

Hardiness

Zone 7+

Soil textures

sandy, loamy, clay

Soil pH

acid, neutral, alkaline, very alkaline

Drainage

well drained

Tolerates Nutritionally Poor Soil

No

Drought

intolerant

Propagation

This section contains historical Plants For A Future notes marked noncommercial.

Cultivation

This section contains historical Plants For A Future notes marked noncommercial.

An easily grown plant, it prefers a well-drained fertile soil in a sunny position^[3], though it succeeds in ordinary garden soil^[1]. Prefers neutral to alkaline conditions^[12]. Plants deplete the soil of nutrients and cannot be grown successfully on the same site for more than two years^[14]. Plants are hardy to about -15°c^[10]. Woad is a biennial, or occasionally a short-lived perennial plant. It has a very long history as a dye plant, being used by the ancient Britons to give a blue colouring to the skin. At one time woad was widely cultivated for this blue dye obtained from its leaves but with the advent of chemical dyes it has fallen into virtual disuse^[14]. It is currently (1993) being grown commercially on a small scale in Germany as a wood preservative (An item on BBC's Radio 4 Farming Programme). Plants self-sow freely when they are grown in a suitable position^[3], though they tend not to thrive if grown in the same position for more than two years^[12].

Related plants

• Isatis glauca
• Isatis japonica
• Isatis lusitanica
• Alliaria petiolataGarlic Mustard

References

1. F. Chittendon. RHS Dictionary of Plants plus Supplement. 1956 Oxford University Press 1951-00-00

   ↩

2. Polunin. O. Flowers of Europe - A Field Guide. Oxford University Press 1969-00-00 ISBN 0192176218

   ↩

3. Holtom. J. and Hylton. W. Complete Guide to Herbs. Rodale Press 1979-00-00 ISBN 0-87857-262-7

   ↩1↩2↩3

4. Niebuhr. A. D. Herbs of Greece. Herb Society of America. 1970-00-00

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5. Buchanan. R. A Weavers Garden.

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6. Clapham, Tootin and Warburg. Flora of the British Isles. Cambridge University Press 1962-00-00

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7. Yeung. Him-Che. Handbook of Chinese Herbs and Formulas. Institute of Chinese Medicine, Los Angeles 1985-00-00

   ↩1↩2↩3↩4

8. Kunkel. G. Plants for Human Consumption. Koeltz Scientific Books 1984-00-00 ISBN 3874292169

   ↩

9. Reid. B. E. Famine Foods of the Chiu-Huang Pen-ts'ao. Taipei. Southern Materials Centre 1977-00-00

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10. Huxley. A. The New RHS Dictionary of Gardening. 1992. MacMillan Press 1992-00-00 ISBN 0-333-47494-5

    ↩1↩2

11. Duke. J. A. and Ayensu. E. S. Medicinal Plants of China Reference Publications, Inc. 1985-00-00 ISBN 0-917256-20-4

    ↩1↩2↩3↩4↩5

12. Bown. D. Encyclopaedia of Herbs and their Uses. Dorling Kindersley, London. 1995-00-00 ISBN 0-7513-020-31

    ↩1↩2↩3↩4↩5↩6↩7↩8↩9↩10↩11↩12

13. Phillips. R. & Foy. N. Herbs Pan Books Ltd. London. 1990-00-00 ISBN 0-330-30725-8

    ↩1↩2

14. Grieve. A Modern Herbal. Penguin 1984-00-00 ISBN 0-14-046-440-9

    ↩1↩2↩3

15. Uphof. J. C. Th. Dictionary of Economic Plants. Weinheim 1959-00-00

    ↩

16. Schery. R. W. Plants for Man.

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17. Mabey. R. Plants with a Purpose. Fontana 1979-00-00 ISBN 0-00-635555-2

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