Ground tissue#Sclerenchyma

A Sklereide or Sklerenchymzelle (Greek σκληρός skleros "hard" ) in plants is usually a dead cell, which has a greatly thickened cell wall, however, is not formed fibrous. Sclereids are often used to consolidate and gain of parts of plants. You can individually occur (as idioblast ) or a strengthening tissue ( sclerenchyma ) form. Sclereids have a thick secondary cell wall, which is strongly lignified. They have numerous simple pits. Their shape is very variable.

Occurrence

Sclereids are present in the epidermis, the ground tissue and vascular bundles in.

In Stems sclereids occur frequently in the form of a Sklerenchymzylinders around the vascular bundles and often arise from parenchymal cells. In the bark of about Trochodendron Pseudotsuga taxifolia or branched sclereids occur.

In leaves sclereids occur in many forms. In the mesophyll there are two distribution patterns: diffuse distribution in the leaf tissue ( approximately at Olea or Pseudotsuga) or limitation to the ends of the small vascular bundles ( about some Polygalaceae, Capparaceae, Rutaceae ). The star-shaped sclereids of the Nymphaeaceae project into the large intercellular spaces of these species. The sclereids of the olive tree ( Olea europaea) are exceptionally long with about one millimeter.

The fruits of pear (Pyrus ) and quince ( Cydonia ) have stone cells distributed in the fruit flesh. The Tüpfelkanäle are often branched, since inward unite two pits at the cell wall growth. In apples (Malus ) sclereids sit in the core.

In seed hardening of the seed coat is often the fact that develop the epidermis and partly also the underlying cell layers to sclereids.

Molding

According to their shape following classification can be made:

• Brachysklereiden or stone cells are nearly isodiametric. They occur mainly in fleshy fruits in groups. In walnut fruit and stone fruit, they form the hard layer.
• Makrosklereiden or rod cells are elongated cells and are mostly found in fruit and seed trays. This includes the Malpighian cells of the Fabaceae.
• Osteosklereiden are elongated cells and widened or lobed at the ends. They occur particularly on in leaves.
• Astrosklereiden are branched, often stellate cells. they are mostly found in leaves of Nymphaeaceae and some monocotyledonous aquatic plants.
• Trichosklereiden are long, pointed, hair-like, sometimes slightly branched cells.

Documents

• Gerhard Wagenitz: Dictionary of Botany. 2nd Edition, Spektrum Akademischer Verlag, Heidelberg, Berlin, 2003, pp. 297 ISBN 3-8274-1398-2
• Katherine Esau, Anatomy of Seed Plants. John Wiley, 1960, pp. 55-58.

• Cell type