Ground Tissue in plants- Sclerenchyma

I have posted about Parenchyma and Aerenchyma in response to one of the students question .. But I dont think it is complete without the notes on an overall types of Ground tissue in plants....So lets have a look at the overall facts about Ground tissue in plants:

The types of ground tissue found in plants develop from ground tissue meristem and consists of three simple tissues:

1. Parenchyma (cells with thin primary walls that retain their protoplasm)
2. Collenchyma (cells with thick primary walls that retain their protoplasm)
3. Sclerenchyma (cells with lignified secondary walls that have lost their protoplasm at maturity, i.e. are 'dead')

...So I' m going to discuss here about Sclerenchyma :

Sclerenchyma is a supporting tissue in plants.

Two groups of sclerenchyma cells exist:

Fibres and Sclereids.

Their walls consist of cellulose, hemicellulose and lignin.

Sclerenchyma cells are the principal supporting cells in plant tissues that have ceased elongation. Sclerenchyma fibres are of great economical importance, since they constitute the source material for many fabrics (flax, hemp, jute, ramie).
Unlike the collenchyma, mature sclerenchyma is composed of dead cells with extremely thick cell walls (secondary walls) that make up to 90% of the whole cell volume.

The term "sclerenchyma" is derived from the Greek σκληρός ("sklē-rós"), meaning "hard".

It is the hard, thick walls that make sclerenchyma cells important strengthening and supporting elements in plant parts that have ceased elongation.

The difference between fibres and sclereids is not always clear.

(As for your SPM scope, you need not know about it so details )

Fibres usually originate from meristematic tissues.

Cambium and procambium are their main centers of production.

They are usually associated with the xylem and phloem of the vascular bundles.

The fibres of the xylem are always lignified, while those of the phloem are cellulosic.

Sclereids are small bundles of sclerenchyma tissue in plants that form durable layers, such as the cores of apples and the gritty texture of pears.

Sclereids are variable in shape.

But compared with most fibres, sclereids are relatively short

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