Gum Resin, a natural mixture of gum and resin that is obtained from the leaves and bark of certain plants. Gum resin does not dissolve in water and usually has a strong smell and taste. The resins and oils in a gum resin are more useful than the gum. The oils impart a distinctive odor, and often a color, to other materials. Important gum resins are gum ammoniac, asafetida, frankincense, gamboge, and myrrh. These substances have a variety of uses in medicine and pharmacy and in the manufacture of perfume.