Sclerenchyma

Abstract

Sclerenchyma is a specialised tissue, adapted to withstand both compressive and tensile stresses in plants. Sclerenchyma cell types may be divided into fibres, associated with phloem, xylem and other tissues; and sclereids or varied kinds. Sclereids originate from parenchyma and expand by intrusive growth. Phloem and xylem fibres in trees originate from the vascular cambium through delicately controlled, parallel cell divisions. Sclerenchyma cells have secondary wall layers that are constructed from cellulose microfibrils in a matrix of hemicelluloses and lignin. The cell geometry and the orientation of the cellulose are tailored to provide diverse combinations of strength, flexibility and stiffness in plant organs subjected to different loads by gravity, wind and weather. These properties are utilised in wood textiles and other natural materials of commercial importance.

Key Concepts:

  • Sclerenchyma is a plant tissue providing mechanical stiffness and strength.

  • Fibres and sclereids are the main types of sclerenchyma cells.

  • Most sclerenchyma cells show intrusive growth.

  • The cell walls of sclerenchyma have thickened secondary layers made from cellulose, hemicelluloses and lignin.

  • The stiffness of sclerenchyma depends on the orientation of cellulose and varies widely under developmental control.

  • Formation of sclerenchyma is controlled by a range of transcription factors.

Keywords: fibre; sclereid; strength; stiffness; secondary cell wall; lignin; lignocellulose; vascular cambium; intrusive growth

Figure 1.

Phloem fibres of flax (Linum usitatissimum) in transverse section. The thick‐walled fibre cells (red) are attached together in bundles. Some are of small diameter: the plane of the section passes through these close to their intrusively growing tips, where they are tapering towards a point.

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Further Reading

Esau K (1965) Plant Anatomy, 2nd edn. New York: Wiley.

Metcalfe CR (1979) Some basic types of cells and tissues. In: Metcalfe CR and Chalk L (eds) Anatomy of the Dicotyledons, vol. 1, pp. 54–56. Oxford: Clarendon Press.

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How to Cite close
Jarvis, Michael C(Aug 2012) Sclerenchyma. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0002082.pub2]