Bark

Eucalypt bark

Monterey Pine bark

Bark of a Pine tree in Tecpan, Guatemala.

The word is often used in a general way to designate the softer outer envelope of a stem or root. In this sense, it includes all that peels readily, as the bark of the hemlock and oak, used for tanning leather. In a stricter sense, it is applied to the corky layers formed on the outer surface of woody plants. It is formed from an active layer of tissue,—the phellogen. The bark is developed in different ways on different trees. So distinct are the resulting tissues that species of trees may be readily recognized by their bark alone. Cork of commerce is the bark of the cork oak, a native of southwestern Europe. Inasmuch as the word covers so many structures, it is little used by botanists in technical descriptions.

This article contains a definition from the Glossary of Gardening Terms.