[Biology Class Notes] on Difference Between Monocot and Dicot Root Pdf

Based on the number of cotyledons, all vascular plants are classified into dicots and monocots. Most monocotyledons are angiosperms and the seed contains one embryonic leaf. Some examples are ginger, onions, and wheat. Dicotyledons have two embryonic leaves on the seed. Some examples are pea, lentils, beans, etc. The root system of both these types of plants has unique, distinguishable characteristics. We will study them in this article. The anatomy of monocot and dicot roots are explained in the article. 

Monocot Root

A monocot root shows 5 distinct regions. We will discuss each of them in the following. The components of the monocot root system are described below. 

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Epiblema

This is the single outermost layer of the root made entirely from parenchymatous cells and does not have any intercellular space. It bears unicellular epidermal root hairs with less cutin and more cuticles. This region of the monocot root is also known as rhizodermis.

Cortex

It is made up of multi-layered oval parenchymatous cells and has intercellular spaces. These spaces help in the gas exchange and storage of starch. In monocots, a few layers of cortex below the epiblema give rise to a layer called exodermis which is made from multi-layered cuticularised sclerenchyma cells.

Endodermis

It is the innermost layer of the cortex made of barrel-shaped parenchyma. It shows a ring-like formation around the stele and the cells are characterized by Casparian stripes. Due to the presence of Casparian stripes, endodermis forms a water-tight jacket around the vascular tissue, therefore it is also called a biological barrier. Endodermis regulates both the inward and outward flow of water and minerals and prevents the diffusion of air into xylem elements.

Pericycle

It is made from thin-walled parenchymatous cells and is the outermost layer of the stellar system. The cells can become sclerenchymatous in older roots. Numerous lateral roots arise from this layer.

Vascular Bundle

The xylem and phloem systems are found in different radii alternating with each other in this region. The numbers of these systems vary from 8-46. The protoxylem lies towards the periphery whilst the metaxylem lies towards the centre. The protoxylem has spiral thickening and the metaxylem has pitted thickening. The phloem consists of sieve tubes, phloem parenchyma, and companion cells. The region functions as a transportation system of elements within the plant body. 

Conjunctive Tissue

It is made of parenchymatous tissue and separates the xylem and phloem system.

Pith

It is a large well-developed part of the monocot root and is made up of thinly walled parenchymatous tissue. It contains high amounts of starch grains.

Dicot Plant Root System

The following are the distinguishing features of the dicot root system. The five distinct regions are as same as the monocot root system which are described below. 

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Epiblema

It is uniseriate, colourless, thin-walled, and without intercellular spaces.  The epiblema produces unicellular root hairs.  Stomata and cuticle are absent.

Cortex

It is thin-walled and made from polygonal or circular parenchymatous cells that usually have intercellular spaces. It is responsible for the transportation of salts and water from root hairs to the centre of the root.

Endodermis

It is made of barrel-shaped compact parenchymatous cells and gas both passage cells and Casparian stripes. This region allows the radial diffusion of water and minerals through the endodermis.

Pericycle

It is composed of a uniseriate layer of parenchymatous cells without intercellular spaces. Lateral meristem and lateral roots grow from the Pericycle region. 

Vascular Region

The bundles are radial. The xylem system consists of tracheids, vessels, xylem fibres and xylem parenchyma. The phloem system consists of sieve tubes, phloem parenchyma and companion cells, Phloem fibres are absent or reduced. 

Pith

It is centrally located and is very small and is made of polygonal parenchymatous cells. It functions as a storage unit of food.

Differentiation between Monocot Root and Dicot Root

The differences between dicot root and monocot root are enumerated below

In conclusion of the article, we have learnt about the difference between monocot and dicot root systems. We have also learnt about the anatomy of both types of root systems.