Permanent Tissue Notes

Permanent Tissue

Permanent Tissue Definition: The tissues that are composed of mature cells derived from meristematic tissues which have lost their dividing property are known as permanent tissues.

Permanent Tissue  Distribution: Permanent tissues are found all over the plant body.

Permanent Tissue  Characteristics:

1. Mature cells are unable to divide.
2. These cells are either living or dead.
3. Living cells contain protoplasm while the dead cells lack it.
4. the cells have thin or thick cell walls. thick cell walls often show various ornamentations due to plate meristem uneven deposition of cell wall materials.
5. Cells are of definite shapes and are vacuolated.
6. The cells may be homogeneous (cells are similar in size, shape, and structure) or heterogeneous (cells differ in size, shape and structure).
7. Intercellular space may or may not be present.

Read and Learn More: WBCHSE Notes for Class 11 Biology

Permanent Tissue  Function:

1. Food production,
2. Food and water storage,
3. Provide mechanical support,
4. Transports water, dissolved minerals and food.
5. Secretion and excretion of different substances.

” how many types of simple permanent tissue “

Permanent Tissue  Classification: Based on organisaion and function, permanent tissues are of three types—simple permanent tissue, complex permanent tissue and secretory tissue.

Simple permanent tissue

Simple permanent tissue Definition: The tissues that are composed of the same type of cells and are thus homogeneous are known as simple permanent tissues.

Simple permanent tissue Types: There are three types of simple permanent tissues in plants.

1. Parenchyma,
2. Collenchyma and
3. Sclerenchyma. Details are given in the following chart.

“simple permanent tissue function “

Parenchyma

Parenchyma Definition: The term parenchyma refers to simple permanent tissue, composed of isodiametric, living and thin-walled cells, that have cell walls made up of cellulose.

Parenchyma Origin: Parenchyma cells originate from protoderm and ground meristem. Secondary parenchyma cells originate from secondary meristems. Parenchyma cells of vascular bundles originate from the procambium.

“what are complex permanent tissues “

Parenchyma Distribution: It is the most common simple permanent tissue in plants and occupies major portions of the plant body. Parenchyma mainly occupies the softer, non-woody portions of the plant body like the epidermis of root, stem and leaves, cortex of root and stem, mesophyll of leaves, pulp of the fleshy fruits, embryo and endosperm of the seeds, etc.

Parenchyma Characteristics:

1. At the beginning of a plant’s life, during embryo development parenchymatous tissues develop.
2. Parenchyma is composed of isodiametric cells with very prominent intercellular spaces.
3. The cells have functional protoplasts with nuclei.
4. These tissues are connected with various physiological functions of the plant.
5. Individual parenchyma cells usually have thin walls which are made up of cellulose.
6. The internal structure of the parenchyma cells varies according to its function
7. The parenchyma cells possess a distinct nucleus and the cytoplasm is vacuolated.
8. In the matured parenchymatous cell cytoplasm remains as a primordial cuticle because of the presence of a large central vacuole.
9. Parenchyma cells may be oblong and arranged in parallel as in the palisade cells of the mesophyll tissue, in the medullary rays, etc They may be multilobed or folded as found in spongy cells of the mesophyll tissue.
10. The non-green parenchyma cells contain leucoplasts.
11. In storage regions of plants, the cell walls of parenchyma may be thick due to hemicellulose deposition, as found in the endosperm of date palm seeds. Primary pit fields may be present in the wall.
12. Parenchyma tissue is considered to be primitive as the multicellular plants of the lower groups consist only of parenchyma.
13. It is the fundamental tissue of the plant body as it provides the ground for other tissues. Parenchyma tissue is the precursor of all other tissues. So, the parenchyma tissue is considered to be the most primitive tissue, both phylogenetically and ontogenetically.

“chloroplast is present in permanent tissue “

“two types of tissue in plants “

Parenchyma Types: On the basis of structure and function, parenchyma is classified into the following types—

1. Chlorenchyma: The parenchyma cells, usually observed in the cortical region of young stems and mesophyll tissue of leaves contain chloroplasts and are called chlorenchyma. These tissues take part in photosynthesis. In leaf, chlorenchyma is of two types, palisade and spongy parenchyma.
2. Aerenchyma: A spongy, parenchymatous tissue with large air spaces found in the intercellular spaces of cortical regions of aquatic plants is known as aerenchyma. The aerenchyma cells store air to provide buoyancy in an aquatic environment and allow the circulation of gaseous substances.
3. Prosenchyma: The parenchyma cells which become elongated and thick-walled, are known as prosenchyma. These cells are found in the pericycle region and provide mechanical strength to the plants.
4. Idioblast: There are certain specialised parenchyma cells containing oils, tannins, crystals of calcium oxalate, etc., which are called idioblasts. These cells act as storage of reserves, excretory material, pigments etc. They differ from the surrounding cells in size, content and functions.
5. Stellate parenchyma: The star-shaped parenchyma cells with long arms and air cavities are called stellate parenchyma. These cells are found in the stems of Scirpus, Juncus, etc., and in the mesophyll tissues of Canna leaves.
6. Xylem and phloem parenchyma: In vascular bundles, two types of parenchyma are found—xylem and phloem parenchyma. Xylem parenchyma helps in the transportation of water, and dissolved minerals and phloem parenchyma transport food, as components of the xylem and phloem tissues respectively.

“simple tissue and complex tissue difference “

“simple tissue definition “

Parenchyma Function:

1. Parenchyma cells in the mesophyll tissue manufacture food through photosynthesis.
2. Xylem and phloem parenchyma are involved in the transport of water, dissolved minerals and food respectively.
3. Epidermal cells of stems, roots and leaves protect the inner tissues from desiccation.
4. Aerenchyma in aquatic plants gives buoyancy, helps in gaseous exchange and to withstand mechanical stress in aquatic environments.
5. Parenchyma cells also help in the secretion and storage of various useful products like oils, nectar, resin, etc.
6. They can store food and water.
7. Parenchyma cells play an important role in the healing of wounds and regeneration of damaged tissues.
8. Prosenchyma provides mechanical strength to the plants.
9. Epidermal parenchyma of the leaves is modified to form guard cells and stomata.