Draw illustrations to bring out the anatomical difference between Monocot root and Dicot root.
 

(i) A tissue is a group of cells having a common origin and performing a common function.

(ii) A plant is made up of different kinds of tissues. The plant tissues are classified into two main groups, namely meristematic and permanent.

(iii) Growth in plants is largely restricted to specialised regions of active cell division called meristems.

(iv) The meristematic tissues are differentiated depending on location, function, origin, and plane of cell division.

(v) The tissues are well-marked on the basis of position as apical, intercalary, and lateral meristems.

(vi) When both primary and secondary meristems divide, the newly formed cells become structurally and functionally specialised and lose the ability to divide. Such permanent cells constitute permanent tissues.

(vii) The permanent tissues are of a simple, complex, and secretory nature.

(viii) The simple tissues are parenchyma, collenchyma, and sclerenchyma.

(ix) The complex tissues include the xylem and phloem.

(x) The secretory tissues are of external and internal nature, and they produce substances of cytoplasmic origin, such as digestive enzymes (in insectivorous plants), nectar, resin, latex, etc.

(xi) The main functions of simple and complex tissues are the assimilation of food and its storage, transportation of water, minerals, and food, and also mechanical support.

2. The Tissue System: 

(i) There are three types of tissue systems: epidermal, ground, and vascular.

(ii) Epidermal tissue system includes epidermal cells, stomata, and epidermal appendages.

(iii) The ground tissue system is mostly parenchymatous and forms the main bulk of the plant body.

(iv) The vascular tissue system is composed of the xylem and phloem surrounded by the pericycle.

(v) The xylem has two main components: tracheids and vessels, which are collectively called tracheary elements.

(vi) The phloem is also made of two main components-sieve tube elements and companion cells.

(vii) The vascular system forms the conducting tissue and translocates water, minerals and the food material.

3. Anatomy of Dicotyledonous and Monocotyledonous Plants:

(i) Monocotyledon and dicotyledon plants show marked variation in their internal structure of stem, root, and leaf.

(ii) The secondary growth is normally a feature of the dicot stem and dicot root. However, it has also been reported in some monocot stems.

(iii) The activity of cambium produces secondary phloem and secondary xylem (wood).

(iv) Cork cambium can also be called phellogen, and cork is called phellem. Secondary cortex has an alternate term known as phelloderm.

(v) Phellogen, phellem and phelloderm are collectively known as periderm which is protective in function.

(vi) The cork cells have a wax-like deposition of suberin, and due to this, it is impervious to water.

4. Secondary Growth:

(i) The activity of the cambium is influenced by seasonal variations in temperate regions.

(ii) In spring, the cambium is more active, producing a large amount of xylem with wider vessels, and such wood is called spring wood.

(iii) On the contrary, the activity of cambium in winter is reduced, producing a lesser amount of xylem with narrow vessels. Such wood is called autumn wood.

(iv) The two kinds of wood in the form of spring wood and autumn wood appearing as concentric rings in a single year is called an annual ring.

(v) The age of the plant can be estimated by counting annual rings, and the method of age determination is called dendrochronology.

(vi) The number of annual rings is equal to the age of the plant.

(vii) In the stem of old trees, the two regions are clearly demarcated, the central dark-coloured heartwood and peripheral light coloured sapwood.

(viii) Heartwood is not suitable for water conduction, while sapwood is suitable for transporting water and minerals.

(ix) Balloon-like ingrowths in the lumen of either tracheids or vessels are called tyloses.

(x) Various types of plant products like oils, resins, gums, aromatic substances, essential oils, and tannins are deposited in the cells of the heartwood. These substances are collectively called extractives.