Tragacanth

Tragacanth is a natural gum taken from the dried sap of several Middle Eastern species of Astragalus, legumes that include A. adscendens, A. gummifer and A. tragacantha; some are known together as goat's thorn, and the name joins the Greek words for goat and thorn. Grieve describes A. gummifer as a small, branching, thorny shrub of Asia Minor, Persia and Kurdistan, and Iran is now the largest producer. Sap drained from the root seeps out in twisted ribbons or flakes, horny in look, nearly colourless or faintly yellow, odourless and almost tasteless. In water it swells into a gel rather than dissolving: one part, tragacanthin, forms a mucilage, while the other, bassorin, only swells. That gel makes it a thickener and stabiliser in foods and medicines, the traditional binder of artists' pastels, a size for paper marbling, a paste for sugar flowers on cakes, and a burnishing compound in leatherwork. Incense makers use it to bind powdered herbs, and it holds them so well that half as much is needed as of gum arabic. Older medicine gave it for coughs and diarrhoea and spread its mucilage on burns. Cunningham assigns it to fire and to the Earth and lists binding among its powers; he suggests blending it with symbols of the ethereal to fill a dream pillow, carrying the ethereal into the subconscious.