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Macro and Microscopic Structure of ROOTs

-Dr.Manjunath Ajanal PG Scholar KLEU Shri BMK Ayurveda College Belgaum

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Introduction

• The plant world is extremely diverse,

ranging from one celled algae to huge

oaks and sequoias.

• Roots is the descending part of the

plant and is originally the direct

prolongation of the radicle of the

embryo.

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• Root is one of the imp structure

present in all most every plants.

• It is non green structure without

node and inter nodes, leaves or

buds of plant.

• These are helps in absorption of

raw food for plants.

• Some times stores food also.

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Embryonic root or radicle

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Root System

• Taproot System:Characterized by having one main root from which smaller branch roots emerge. 

• Fibrous Root System:extensive mass of similarly sized roots

• Adventitious roots are roots that form on plant organs other than roots. 

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Anatomy of roots• Root cap – Derived from

cells of meristem that pushes cells forward into the cap region these secretes MUCIGEL – protection.

• Root Tip Senses Gravity

• Region of cell division - primary growth of the root

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Anatomy of roots

• Region of elongation - The cells derived from the apical meristem increase in length in this region.

• Region of differentiation or maturation - cells become specific tissues-epidermis, cortex, or vascular tissue.

Root Cap

Zone of Cell Division

Growing out through cortex

•In fibrous root systems, there is much lateral root formation.

•Here two root apices initiating from the pericycle.

•Their connection to the ridges is xylem

Root Anatomy: Dicot Root Cross Section

Epidermis - root hairs, mineral and water intake

Cortex - storage, defense

Endodermis - selective mineral uptake

Pericycle - lateral root formation (periderm)

(Vascular Cambium - makes 2° tissues)

Phloem - CH2O delivery from leaves

Xylem - conduct water and mineral upwards

Casparian strips in radial walls

One Vascular Cylinder (Phloem + (Cambium) + Xylem)Radial Xylem-Phloem ArrangementExarch Xylem MaturationTetrarch (this example)

Dicot Mature Root Structure - AnatomyEpidermis

Cortex

Vascular Cylinder

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Root Anatomy: Monocot Root Cross Section

cortex Phloem Xylem pith

Pith

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DIFFERENCES DICOT ROOT

The radicle of embryo develops into root – Entire root system develop from this.

The root system is called a primary or tap root.

The root system is deep growing and hence called deep feeders.

Xylem bundles – 2 to 6 Root has a narrow pith with

exarch and tetrach xylem.

MONOCOT ROOT The radicle emerges out into

root ; but soon withers off. Extra – embryonal roots arise forming fibrous roots.

The root system is called fibrous or adventitious root.

The root system is not deep & hence called shallow feeders.

Numerous rarely limited. Monocot root has a wide

pith and exarch and polyarch xylem.

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Secondary Growth in Dicot Roots

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Secondary Growth in Dicot Roots

Cambium-is a layer of meristematic tissue that separates the xylem and phloem and produces new xylem and phloem cells.

Heartwood-Older, nonconducting rings of xylem at the center of the tree’s trunk or root

Sapwood-outer ring of xylem that still transport xylem sap

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MODIFICATION OF ROOTSSpecialized functions of varied nature are

performed by modified roots which adapt themselves according to the particular need of the plant.

For these purposes both the TAP root and the ADVENTITIOUS roots may undergo modification.

1. Modified TAP ROOTS (For storage of food)

2. Modified ADVENTATIOUS ROOTS

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Modified TAP ROOTS1. Fusiform Root : Swollen in

middle and gradually tapering towards apex and the base. E.g. – Radish.

2. Napiform Root: Considerbaly swollen at the upper part becoming almost spherical & sharply tapering at lower part. E.g. - Turnip & Beet.

3. Conical Root: Broad at base & gradually tapering. E.g.- Carrot.

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Modified ADVENTATIOUS ROOTS

A). FOR STORAGE OF FOOD : 1. Tubercular root

swollen with out any definite shape – sweet potato.

2. Fasciculated root several tubercular roots occur in cluster at the base of the stem – Asparagus, Dahlia etc

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3. Nodulose root : When the slender root becomes suddenly swollen near apex – Mango ginger, arrowroot

4. Moniliform/beaded: Swelling at frequent interval – Indian spinach, Musta etc

5. Annulated : root has a series of ring like swelling on its body - Ipecac

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B). FOR MECHANICAL SUPPORT1.Prop or slilt root : roots produced from stem, grow vertically downwards and penetrate in to soil. E.g – Vata, rubber plant, screwpine

2.Climbing roots : these plants produce roots from their nodes, internodes by this they attach themselves for support & climb. E.g.- pippali, maricha etc.

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C). FOR VITAL FUNCTION1.SUCKING ROOTS: Parasites develop certain kinds of roots which penetrate into the tissue of the host plant and suck it. E.g.- broomrape etc.2.RESPIRATORY ROOTS: Aquatic plant develops kind of adventatious roots which are colourless & soft they develops at the level of water. E.g- Jussiaea etc.

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3.EPIPHYTIC ROOTS: These are grow on branches of trees, they do not suck the supporting plant but these are having modified roots which are hang freely in air. E.g- Orchids.

4.Assimilatory roots: Some climbing plant are produced long slender hanging roots with chlorophyll - turns to green these are helps for production of food. E.g- Some orchids, water chestnut etc.

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FUNCTIONS AND ADAPTATIONS OF THE ROOT

NORMAL FUNCTIONSMechanical

Fixation Physiological

AbsorptionConductionStorage

SPECIALIZED FUNCTIONS – Connection with modified roots.

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CONCLUSION

Study of botany is very imp in ayurvedic field.

Helps in cultivation of medicinal plants.

Detection of age of plant.For easy identification of

Adulteration.

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