Tragacanth

a mucilaginous substance or gum obtained from certain spiny shrubs of Asia Minor and adjacent regions. These plants belong to the genus astragalus. Unlike other gums, tragacanth exudes not from sap or the bark but bursts forth from the pith, forming threads and flakes which may be gathered from the branchlets. Gum tragacanth is odorless and nearly tasteless. Disintegrated in water, for it will not dissolve, it forms desirable but expensive mucilage. It is used by pharmacists in the manufacture of pills and by manufacturers to size crapes and calicoes. The bookbinder uses the gum in marbling books.