Practical
Plants

Astragalus gummifer

Tragacanth

a perennial woody evergreen member of the Astragalus genus in the family Leguminosae.

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Taxonomy and growth

Life cycle
perennial
Foliage
evergreen
Woodiness
woody
Height
0.3 m
Spread
0.3 m
Fertility
Bees, Lepidoptera
Flower type
hermaphrodite
Pollinators
Bees, Lepidoptera

Uses

Toxicity

Toxicity warning. The historical record reports a hazard for this plant. Do not use it to decide which parts are safe to eat or use medicinally.

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

Many members of this genus contain toxic glycosides[13]. All species with edible seedpods can be distinguished by their fleshy round or oval seedpod that looks somewhat like a greengage[15]. A number of species can also accumulate toxic levels of selenium when grown in soils that are relatively rich in that element[13].

Edible uses

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

A source of a high quality gum tragacanth - used as a thickener in confections, salad dressings, sauces etc[6][10][11][12][2][3]. It is an approved additive to food and has the E number E413[8]. Some of the gum exudes naturally from the root and from damaged stems[5], more can be obtained by incision of the stem about 5cm below ground level[12].

Product or use
Gum

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.

The gum obtained from the root and stem is demulcent, though it is not often used internally because it is not completely soluble[10]. This gum has recently been shown to stimulate the immune system and to suppress tumours[8]. The gum has long been employed externally as a dressing for burns and is also used in lozenges in order to bind the ingredients and impart consistency to the product[10].

Product or use
Adaptogen
Product or use
Antitumor
Product or use
Demulcent

Material uses

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

Gum tragacanth is obtained from the stem (see above). It has a wide range of uses including:- a thickening agent in preparing dyes for calico printing, textile dyes and for dressing fabrics, it is also a thickener in making glues, water colours, ink (where it supplies a gloss), it is a binding agent in paper making, a culture medium in laboratories etc[12][14]. Both the stems and the gum can be burnt as a fragrant incense[9].

Product or use
Gum
Product or use
Incense
Product or use
Size

Ecology and functions

Nitrogen fixer

Environment

Range
W. Asia - Iraq, Kurdistan
Habitat
Dry sub-alpine slopes and valleys, occasionally below the tree line, 1200 - 2600 metres in Iraq[3]. Upland forests and grassland[8].
Light
full sun
Shade tolerance
no shade
Water
low
Hardiness
Zone 8+
Soil textures
sandy, loamy
Soil pH
very acid, acid, neutral, alkaline
Drainage
well drained
Tolerates Nutritionally Poor Soil
No
Drought
intolerant

Propagation

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

Seed - best sown as soon as it is ripe in a cold frame[7]. A period of cold stratification may help stored seed to germinate[7]. Stored seed, and perhaps also fresh seed, should be pre-soaked for 24 hours in hot water before sowing - but make sure that you do not cook the seed[4][7]. Any seed that does not swell should be carefully pricked with a needle, taking care not to damage the embryo, and re-soaked for a further 24 hours[4][7]. Germination can be slow and erratic but is usually within 4 - 9 weeks or more at 13°c if the seed is treated or sown fresh[4]. As soon as it is large enough to handle, prick the seedlings out into individual pots and grow them on in the greenhouse for their first winter, planting them out into their permanent positions in late spring or early summer, after the last expected frosts.

Cultivation

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

Requires a dry well-drained soil in a sunny position[1][8]. Succeeds in poor soils[7]. Tolerates a pH in the range 3.2 to 7.8. This species is not hardy in the colder areas of the country, it tolerates temperatures down to between -5 and -10°c[8]. Whilst it is likely to tolerate low temperatures it may not be so happy with a wet winter. Plants are intolerant of root disturbance and are best planted in their final positions whilst still small[7]. This plant is a sub-shrub and although it produces woody stems these tend to die back almost to the base each winter. This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby[7]. Many members of this genus can be difficult to grow, this may be due partly to a lack of their specific bacterial associations in the soil[7].

References

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

    ↩

  2. Tanaka. T. Tanaka's Cyclopaedia of Edible Plants of the World. Keigaku Publishing 1976-00-00

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  3. Chakravarty. H. L. The Plant Wealth of Iraq.

    ↩1↩2

  4. Rice. G. (Editor) Growing from Seed. Volume 2. Thompson and Morgan. 1988-00-00

    ↩1↩2↩3

  5. Hill. A. F. Economic Botany. The Maple Press 1952-00-00

    ↩

  6. Hedrick. U. P. Sturtevant's Edible Plants of the World. Dover Publications 1972-00-00 ISBN 0-486-20459-6

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

    ↩1↩2↩3↩4↩5↩6↩7↩8

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

    ↩1↩2↩3↩4↩5

  9. Genders. R. Scented Flora of the World. Robert Hale. London. 1994-00-00 ISBN 0-7090-5440-8

    ↩

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

    ↩1↩2↩3

  11. Schery. R. W. Plants for Man.

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  12. Howes. F. N. Vegetable Gums and Resins. Faber

    ↩1↩2↩3

  13. Frohne. D. and Pf�nder. J. A Colour Atlas of Poisonous Plants. Wolfe 1984-00-00 ISBN 0723408394

    ↩1↩2

  14. Komarov. V. L. Flora of the USSR. Israel Program for Scientific Translation 1968-00-00

    ↩

  15. Harrington. H. D. Edible Native Plants of the Rocky Mountains. University of New Mexico Press 1967-00-00 ISBN 0-8623-0343-9

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