Fibers are long cells with lignified secondary cell walls.
Their function is for structural support.
Phloem and xylem fibers provide structural support for the stem.
The strength of the fiber comes from the deposition of lignin in the secondary cell wall.
What is lignified?
Cells with secondary cell wall thickening typically contain lignin.
Lignin is a chemical substance that resists breakdown.
Along with cellulose, lignin gives wood its strength.
Cross-section of English ivy (Hedera helix).
Species that produce long fibers are of commercial importance. Fibers are used to make rope, cloth, and paper.
Species that are commercial sources of fibers include cotton, flax, hemp and ramie. An individual fiber can be between 1 to 70 mm long.