Note: Information is dated. Do not rely on it.

Bark. The exterior covering of the stems of exogenous plants. It is composed of cellular and vascular tissue, is separable from the wood, and is often regarded as consisting of four layers: (1) The epidermis or cuticle, which, however, is scarcely regarded as a part of the true bark; (2) the epiphlaeum or outer brown corky cellular layer of the true bark or cortex; (3) the mesophlaeum or green middle layer, also cellular; (4) an inner vascular layer, the liberor or endophllaeum, commonly called bast. Endogenous plants have no true bark. Bark contains many valuable products, as gum, tannin, etc.; cork is a highly useful substance obtained from the epiphlaeum; and the strength and flexibility of bast makes it of considerable value. Bark used for tanning is obtained from oak, hemlock, species of acacia growing in Australia, etc. Angostura bark, Peruvian or cinchona bark, cinnamon, cascarilla, etc., are useful barks.

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