Plant Tissue Functions

Plant Tissue Functions

The group of cells have a common origin and usually perform a common function.

Types of Plant Tissue

A. Meristematic Tissue

Growing regions of the plants are called meristems. Meristematic tissue has the capability of cell division. Daughter cell formed out. It grows and constitutes the different parts of the plant. This process continues till the lifespan of the plant.

Specific Features of Meristematic Tissue

1. It is round, oval or multisided.

2. Its wall is thin, and the cytoplasm is homogeneous.

3. The cell contains dense cytoplasm and a single large nucleus.

4. There is a lack of intercellular spaces between the cells.

Types of Meristems

1. Apical Meristems

• These tissues are found in the root and stem apex, and the initial growth (especially length) of the plant takes place due to this tissue.

2. Lateral Meristems

• Due to the division in these tissues, growth in the girth of roots and stems takes place. Hence, it increases the width of the root and stem.

3. Intercalary Meristems

• They are located at the base of the internode.

• In fact, this is the remains of the apical meristems, which are divided by the incoming of permanent tissues in the centre.

• Plants increase their length by the activity of this. Its importance is for those plants whose apical parts are eaten by vegetarian animals.

• After being eaten, the plants grow with the help of intercalary meristems only. Like – grass.

B. Permanent Tissue

Permanent tissues are made of those mature tissues which have lost the capacity of cell division. These tissues attain definite forms at different places for a definite function. Cells of permanent tissue may be alive or dead.

Permanent tissues are of two types:

I. Simple Permanent Tissue

If permanent tissue is made up of similar types of cells, it is called simple tissue. There are three main types of simple tissue.

a. Parenchyma

• Cells of parenchyma are thin-walled and unspecialised, used for multiple purposes in plants.

• This is found in the inner layer of leaves called the mesophyll. These cells are photosynthetic.

• These cells are also found in the covering of roots and stems. It is also found in the soft part of fruit.

b. Collenchyma

• The cells of collenchyma are elongated, having thick cell walls that help to hold up the plant.

• It also provides flexibility to the stem, allowing it to bend.

c. Sclerenchyma

• The cells of sclerenchyma are dead, having thick cell walls and becoming inflexible, providing mechanical strength to the plant.

II. Complex Permanent Tissue

If the permanent tissue is made up of more than one kind of tissue working together, it is called complex tissue.

a. Xylem

• Xylem is a conduction tissue found in vascular plants made up of tracheids, vessels, xylem parenchyma cells and xylem fibres.

The main functions of xylem are:

• Xylem helps in the transportation of water and minerals from the soil to the stems and leaves.

• It provides mechanical strength to the plant.

• Xylem is wood, which is a valuable raw material.

Additional Information:

• The first-formed primary xylem elements are called protoxylem.

• The second formed primary xylem elements are called metaxylem.

• In stem protoxylem lies towards the centre, and metaxylem lies towards the periphery. This type of arrangement is called endarch.

• The determination of the age of the plants is done by counting annual rings of xylem tissue; this is called dendrochronology.

b. Phloem

It is a living conducting tissue made up of sieve elements, companion cells, parenchyma cells and phloem fibre.

The main functions of phloem are:

• It conducts soluble organic compounds from leaves to different parts of the plant. This kind of transport process is called translocation.

• Phloem is the innermost layer of bark.

• Companion cells of phloem are unique to angiosperms.

Some Other Information About Plant Tissue

• The husk of a coconut is made up of sclerenchyma tissue.

• In aquatic plants there are large air sacs which give them a buoyancy effect and are surrounded by parenchymatous tissue.

• Fibres in relation to plant anatomy are responsible for conduction and mechanical support.

• In the middle layer of the root apical meristem is the periblem, which gives rise to the cortex.

• The wood is actually a secondary xylem.

• Transpiration: It is a process of loss of water from the aerial part of a plant in the form of water vapour.

• The cells which are closely associated and interacting with guard cells are subsidiary cells.

• Transpiration keeps the plant and its surroundings cool.

• The process of the escape of liquid from the tip of a leaf is called guttation.

• The rate of transpiration can be measured by Ganong’s potometer.

Note:

• Cotton fibres are made up of cellulose.

• The silver fibre revolution is associated with cotton fibre.

Final Thoughts

Plant tissues are groups of cells with a common origin and function. They are mainly classified into meristematic and permanent tissues. Meristematic tissues, found in growing regions like root and stem tips, have active cell division and are responsible for the plant’s length and girth. Types include apical, lateral, and intercalary meristems.

Permanent tissues are mature cells that perform specific functions and are of two types: simple (parenchyma, collenchyma, and sclerenchyma) and complex (xylem and phloem).

Xylem transports water and provides strength, while phloem conducts nutrients. Other plant features like transpiration, guttation, and fibres in cotton highlight the diverse roles of tissues in growth, support, and survival.