A group of plant cells performing essentially the same function and common to the similar structure is a plant tissue. On the basis of the stages of development, plant tissues are divided into two types:
The group of young cells which have the capacity of active cell division is called meristem. On the basis of origin, they are classified as primary and secondary meristems.
Those meristems, which are derived directly from the meristems of embryo and responsible for primary growth and lie mainly on the apices of stems and roots, are called primary meristems. They are apical meristems (root apical and shoot apical meristems), intercalary meristems (only in monocots). They help increase the length of the plant.
They are the meristems which are formed as new meristems in permanent cells by re-differentiation and are responsible for increasing the diameter of the plant organ. They are of two types vascular cambium and cork cambium collectively known as lateral cambium (lateral meristem). They help plant to increase its girth. Secondary meristems are divided into three types which are as follows;
They are made up of cells that have lost the power of division and are differentiation to carry out various functions. The permanent tissues are of following types:
These tissues are concerned with manufactured and storage of food and to provide mechanical support to plants. On the basis of structure, it is of following types:
They are made up of different types of cells. The most important complex tissues are xylem and phloem.
They are concerned with the secretion of materials like gums, oils, latex and other substances. They are further subdivided into two groups which are given below,
Lactiferous tissues: These are thin walled,elongated and specialized tube like structures. These ducts are filled with white or yellow latex. They are distributed irregularly in parenchymatous cells. They are responsible for food storage or waste products.
Glandular tissue: It consists if different types of glands which are made of isolated cells or small group of cells. They secrete various digestive enzymes in plants.These secrete resin, oil, mucilage, tannin, gums, nectar etc.
The plant body mainly consists root system and shoot system. The root system lies under the ground whereas the shoot lies above the ground. The root system and shoot system are made of different types of organs. The root system is made of organs like root cap, root tip, lateral root etc. whereas shoot system is made of organs like leaves, stem, flower, fruit, buds etc. Again these organs are made of different types of tissues like parenchyma, (epidermis, cortex, endodermis, and pith), schlerenchyma (pericycle) xylem and phloem (vascular tissues etc.) pericycle, vascular tissues and pith are called stele group. And these tissues are made of different cells.
Tissue is a group of similar cells, which performs specific function. E.g. blood, muscle etc.
The differences between meristematic tissue and permanent tissue are as follows:
|Meristematic tissue||Permanent tissue|
|i) It is classified into primary meristem and secondary meristem.||i) It is classified into simple, complex and special.|
|ii) It is of different shapes without intercellular space.||ii) It is of different shapes with intercellular space.|
|iii) It undergoes mitosis cell division.||iii) It loses the power of division.|
Apical meristematic tissues help in increasing length so if these tissues stop functioning the plant cannot grow further through root as well as shoot.
Simple permanent tissues are of three types:
i) Parenchyma :In all the living areas of plant body.
ii) Collenchyma: It occurs in the peripheral portions of young stems and leaves.
iii) Sclerenchyma: It is found in stems and roots as well as with the veins of leaves, hard outer covering of seeds and nuts.
Complex tissues are a group of different kinds of cells, some of which may differ from each other in structure but work together.
It is mainly of two types:
Parenchyma tissues are made up of thin walled cells, which are living and having shapes like oval or spherical.
Phloem is the storage tissue made by vascular bundle and other components. So, it is called as complex tissue.
A type of complex tissue called xylem transport water from the root to other parts of the plant.
Phloem tissue helps in transportation of prepared food materials from the leaf to storage organs and growing regions too. So, if all these tissues are removed from plant body, energy supply to every cell is stopped and no further activities can perform by plant cell. Ultimately, cell dies which results to the death of plant.
|a) The cells of xylem are thick walled, tubular and often dead.||a) The cells of phloem are tabular and living.|
|b) It consists of four types of cells; Trachea, trachids, wood fibre and wood parenchyma.||b) It consists of four types of cells; sieve tube, companion cells, phloem parenchyma and phloem fibre.|
|c) It transports water and minerals from root to leaves.||c) It transports food material from leaves to different parts of plant body.|
Parenchyma is a type of _________.
Striated muscle is also called ______.