The natural gum tragacanth is the sap of several species of Middle Eastern legumes of the genus Astragalus, including A. adscendens, A. gummifer, and A. tragacanthus. Some of these species are known collectively under the common names "goat's thorn" and "locoweed". The gum is sometimes called "Syrian tragacanth". The name derives from tragos and akantha, which means in Greek "goat" and "thorn", respectively.
Gum tragacanth is a viscous, odorless, tasteless, water-soluble mixture of polysaccharides obtained from sap which is drained from the root of the plant and dried. The gum seeps from the plant in twisted ribbons or flakes which can be powdered. When added to water, tragacanth absorbs water and becomes a gel which can be stirred into a paste. The gum is occasionally used as a stiffener in textiles. It contains an alkaloid that has historically been used as an herbal remedy for such conditions as cough and diarrhea. As a mucilage or paste it has been used as a topical treatment for burns. It is used in pharmaceuticals and foods as an emulsifier, thickener, stabilizer, and texturant. Also, it is the traditional binder used in the making of artist's pastels, as it does not adhere to itself the same way other gums (such as gum arabic) do when dry.
