Bark

Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines, and shrubs. Bark refers to all the tissues outside the vascular cambium and is a non-technical term. It overlays the wood and consists of the inner bark and the outer bark.

Structure

Bark is composed of several layers, each with distinct functions:

• Outer Bark: Also known as the rhytidome, this is the dead outermost layer of the bark. It provides protection against physical damage and prevents water loss.
• Inner Bark: This layer, also known as the phloem, is responsible for the transport of nutrients and sugars produced by photosynthesis from the leaves to other parts of the plant.
• Cork Cambium: Also known as the phellogen, this is a layer of meristematic cells that produce the cork cells of the outer bark.
• Cork: Also known as the phellem, these cells are produced by the cork cambium and form the protective outer layer of the bark.

Functions

Bark serves several important functions for woody plants:

• Protection: Bark protects the plant from physical damage, pathogens, and herbivores.
• Insulation: It helps insulate the plant against extreme temperatures.
• Transport: The inner bark (phloem) is crucial for the transport of nutrients and sugars.
• Storage: Some plants store nutrients and water in their bark.

Uses

Bark has various uses in human activities:

• Medicinal: Certain barks, such as cinchona bark, are used for their medicinal properties.
• Industrial: Bark is used in the production of cork, tannin, and dyes.
• Agricultural: Bark mulch is used in gardening and landscaping to retain soil moisture and suppress weeds.

Types of Bark

Different species of plants have different types of bark, which can vary in texture, thickness, and color. Some common types include:

• Smooth Bark: Found in species like beech and birch.
• Scaly Bark: Found in species like pine and spruce.
• Furrowed Bark: Found in species like oak and elm.

Gallery

• Smooth bark of a beech tree
  Smooth bark of a beech tree
• 
  Scaly bark of a pine tree
• Furrowed bark of an oak tree
  Furrowed bark of an oak tree

See Also

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

External Links

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