astragalus gummifer

Tragacanth \Trag"a*canth\, n. [L. tragacanthum tragacanth,
   tragacantha the plant producing tragacanth, Gr. ? ? a he-goat
   + ? a thorn: cf. F. tragacanthe.]
   A kind of gum procured from a spiny leguminous shrub
   ({Astragalus gummifer}) of Western Asia, and other species of
   Astragalus. It comes in hard whitish or yellowish flakes or
   filaments, and is nearly insoluble in water, but slowly
   swells into a mucilaginous mass, which is used as a
   substitute for gum arabic in medicine and the arts. Called
   also {gum tragacanth}.
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Astragalus \As*trag"a*lus\, n. [L. See {Astragal}.]
   1. (Anat.) The ankle bone, or hock bone; the bone of the
      tarsus which articulates with the tibia at the ankle.
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   2. (Bot.) A genus of papilionaceous plants, of the tribe
      {Galege[ae]}, containing numerous species, two of which
      are called, in English, {milk vetch} and {licorice vetch}.
      {Gum tragacanth} is obtained from different oriental
      species, particularly the {Astragalus gummifer} and
      {Astragalus verus}.
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   3. (Arch.) See {Astragal}, 1.
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