Everything Life Sciences Grade 10

FACT

• Collenchyma
  tissues make
  up the strong
  strands
  observed in
  stalks of
  celery.


• The growth
  of
  collenchyma
  tissue is
  affected by
  mechanical
  stress on a
  plant. For
  instance if
  the plant is
  constantly
  shaken by
  the wind the
  walls of
  collenchyma
  may be
  40–100%
  thicker than
  those that
  are not
  shaken.

FACT
WATCH: Learn
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permanent simple
tissues.
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Collenchyma

Diagram Micrograph

Figure 5.10: Collenchyma cells are thin

walled with lignified corners.

Figure 5.11: Light microscope image of col-

lenchyma cells.

Collenchyma

Structure Function

Cells are spherical, oval or polygonal in

shape with no intercellular spaces.

This allows for close packing to provide

structural support.

Corners of cell wall are thickened, with

cellulose and pectin deposits.

Provides mechanical strength.

Cells are thin-walled on most sides. Provides flexibility, allowing plant to

bend in the wind.

Table 5.3

Sclerenchyma tissue DUMMY

Sclerenchyma is a simple, permanent tissue. It is the supporting tissue in plants, making the

plants hard and stiff. Two types of sclerenchyma cells exist:fibresandsclereids.

Sclerenchyma fibresare long and narrow and have thick lignified cell walls. They provide

mechanical strength to the plant and allow for the conduction of water.

Sclereidsare specialised sclerenchyma cells with with thickened, highly lignified walls with

pits running through the walls. They support the soft tissues of pears and guavas and are

found in the shells of some nuts.

124 5.3. Plant tissues