Bark (botany)

Bark is the outermost layer of a tree, woody shrub, or other plant. It serves as a protective barrier against environmental threats such as insects, disease, and fire. The bark also helps to regulate the plant's water content and temperature.

Structure and Function

Bark is composed of several layers, each with a specific function. The outer bark, or periderm, is the plant's first line of defense against physical damage and disease. It is typically tough and corky, and its color can range from grey to brown. The inner bark, or phloem, transports nutrients from the leaves to the rest of the plant. It is usually softer and more fibrous than the outer bark.

Types of Bark

Different species of plants have different types of bark, which can vary in color, texture, and thickness. For example, the bark of the cork oak is thick and corky, while the bark of the paper birch is thin and peels off in strips. The bark of the cinnamon tree is used as a spice, while the bark of the willow tree contains salicin, a compound used to make aspirin.

Bark and Human Use

Bark has been used by humans for thousands of years for various purposes. It can be used as a material for building, for making cordage, for tanning hides, and for making paper. Certain types of bark, such as that of the cork oak, are harvested commercially. Bark is also used in traditional medicine, and some types of bark, such as cinnamon and quinine, are used as flavorings or medicines.

See Also

• Tree
• Wood
• Cork (material)
• Phloem
• Periderm