Exam Lessons

Supporting Tissues in Plants

Supporting Tissue In Plants

  1. Parenchyma
  2. Collenchyma
  3. Sclerenchyma
  4. Xylem
  5. Phloem


It is made up of living unspecialized plant cell that are rough spherical in shape. Parenchyma tissues are founds in the cortex of stem, phloem. Root, leaf mesophyll, storage tissue and xylem


  1. It gives firmness and rigidity to the stem of herbaceous plant
  2. It can store food and water

They are present in the leaf mesophyll to partake in the synthesis of food.

Collenchyma are found in the primary tissue of plants. The cell of collenchyma are living elongated and unevenly thickened at the corner. The cell are flexible and this allow the bending and twisting strain to which the stem , root and leaves  of plant are often subjected. The collenchyma tissue are location in the cortex of stem and in the hypo dermis just beneath epidermis.


1.They provide strength and support in young drawing plant part such as  stem, petiole and leaf

2.They give flexibility and resilience to the plant i.e enable the plant to bend without breaking

Sclerenchyma Tissue   is composed of two type of cell namely sclerenchyma fiber and sclerenchyma sclereid. Both of them consist of deal cell in which the cell wall are heavily thickened with deposit of lignin. ( A lignin is a substance that provide mechanical strength). The cells of the fiber are narrow polygonal, elongated with tapering end.

The lumens are small because of the thickened wall. The s-fiber are present in the outer region of the cortex and pericycle of stem and in the vascular tissue

Sclerenchyma slereid are heavily lignified cells which are spherical. They are present in all part of the plant e.g cortex, pith, phloem, fruit and seed coat.


-They provide mechanical strength

-They give flexibility to plant and prevent them from breaking easily

-They provide strength, rigidity, hardness and support to plants


The xylem tissue are found in the vascular bundle especially the plant that undergo secondary growth. There are four types of xylem tissues namely:

-Xylem tracheid

-Xylem vessel

-Xylem fiber

-Xylem parenchyma

Of the four, first three are lignified and so provide mechanical support.

Xylem tracheid are non- living elongated tapering cell with thickened lignified wall with  pith  that  allow  the passage of  water and dissolve mineral salt.

Xylem vessel :- are long tubular structure that are formed by the fusion of several  elongated cells which are joined

one on top of another.

Xylem fibers– are similar to the sclerenchyma fiber , they have narrow elongated cell with very thick wall.

Xylem parenchyma– are similar to parenchyma tissue. They are composed of cell with large vacuoles

  Function of Xylem Tissue

  1. The xylem tissue provide support and shape to the plant
  2. The major function of xylem tissue is to conduct water and dissolved mineral salt from the root to the leaves.


The phloem tissue are located within the vascular bundle of all plant, be it in the root, stem and leaf , they are made up of four type of  cells namely

  1. P. sieve ( phloem sieve tube)
  2. Phloem parenchyma
  3. Phloem companion cell
  4. Phloem fiber

The phloem sieve tubes– are made up of elongated row of cylindrical cell which are arranged   vertically. The cell are living and they conduct mainly manufacture food.

Phloem parenchyma– are made up of parenchyma cell which offer strength and support to plant. The cell also help in food storage

Phloem fibers– are special cells which are concerned with strengthening of the organs in which they are present.

Phloem companion cells– are small and short cell which are vertically elongated like the seive tube. They assist in conduction of food substance.


1.The general function of the phloem is to conduct manufactured food from area of the synthesis ( leaf) to the area

where they are needed ( i.e stem root)

2.They also assist to provide support to the entire plant .


The protective tissue of plant is the epidermal cell found on the leaf and stem and as piliferous cell in the root.. The epidermal layer is one cell thick with a protective cell. It prevents the inner cell from injury, infection and water less.

The epidermis cell does not contain chloroplast except in the guard cell which possess chloroplast and therefore can photosynthesis


The part of the stem between the epidermis and vascular bundle of a dicotyledonous stem is called

Cortex. The cortex is made up of three tissue which are( collenchyma) on the outside, a middle( parenchyma) and inner( endoderm). The collenchyma is  about three to four times thick while the parenchyma is made up of thin wall cell with many spaces . Both cells provide strength and support. The endodermis is a single layer which is also referred to as starch sheet.


This layer is found on the outer part of the vascular bundle. It consists of dead lignified cells. It aids to strengthen the cell.

Vascular Bundles.       

These are found in the inner part of the stem. It consist of the xylem, phloem and cambium. The xylem is responsible for conduction of water and dissolved minerals salt from soil to the leaf through the root and stem. The phloem is responsible for the conduction or transfer of manufactured food from the area of their synthesis to the other part of the plant.

Cambium is found between the phloem and xylem. The cambium cell are constantly dividing cell. This increases the size of cell which is called secondary thickening which is responsible for the increase in size of the trunks of many trees.


It is the central part of the stem, it is large and made up of parenchyma and extend between the vascular tissue.

Transverse section {T/S} dicotyledonous stem.

Anatomy Of Dicotyledonous Plants | Support And Transport Systems ...

Difference between Dicot and Monocot plant.

NoDicto stemMonocot stem
1.The tissue below the epidermis  is collenchymaThe tissue below the epidermis is sclerenchyma
2.The size of cortex is wideThe size of the cortex is narrow
3.The pericycle is made up of  sclerenchyma which caps the individual bundleSclerenchyma completely surround each vascular bundle
4.The vascular bundle is few which arrange in a ring of cambiumThe vascular bundle are scattered all over the ground tissue
5.Cambium is presentCambium is absent
6.Secondary growth occursSecondary growth does not occurs
7.Pith is presentPith is absent

tranverse-monocotT/S of monocot stem

Difference between Dicot and Monocot Root

NoDicot RootMonocot Root
1.It has only one star shaped xylem bundle centrally located.It has many xylem bundle radially arranged
2.Pith is absentPith is present
3.Few phloem bundles are presentMany phloem bundles  are present
4.Cambium is presentCambium is absent

File:Figure 30 03 03f.jpgCross section of a monocot root

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