Biology handbook for neet. (Dr Anand Mani)

Anatomy of Flowering Plants

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ÅÑÅTØMÝ ØF DÏÇØTÝLËDØÑØÜS & MØÑØÇØTÝLËDØÑØÜS PLÅÑTS

DÏÇØTÝLËDØÑØÜS (DÏÇØT) RØØT

Transverse section of the sunflower

root shows the following tissue

organization:

Epidermis/Epiblema:

The

outermost

layer.

Many

epidermal cells protrude in the

form of unicellular root hairs.

Cortex: It consists of several

layers

thin-walled

parenchyma

cells

with

intercellular spaces.

Endodermis: Innermost layer of the cortex. It comprises a single layer of

barrel-shaped cells without intercellular spaces.

The tangential as well as radial walls of the endodermal cells have a

deposition of water impermeable, waxy material-suberin-in the form of

casparian strips. (NEET 2018)

Stele: All tissues on the inner side of the endodermis together constitute

stele. They include

Pericycle: A few layers of thick-walled parenchymatous cells next to

endodermis. Initiation of lateral roots and vascular cambium during the

secondary growth takes place in these cells.

Pith: Innermost region of the stele. It is small or inconspicuous.

Conjunctive tissue: The parenchymatous cells which lie between the

xylem and the phloem.

Vascular bundles: 2-4 xylem & phloem patches. Later, a cambium ring

develops between the xylem & phloem.

MØÑØÇØTÝLËDØÑØÜS (MØÑØÇØT) RØØT

It has epidermis, cortex,

endodermis, pericycle,

vascular bundles and

pith.

As compared to the

dicot root which have

fewer xylem bundles,

There are usually more

than

six

(polyarch)

xylem bundles (AIPMT

Mains 2012) Phloem

parenchyma is absent.

Metaxylem

Protoxylem

Pith

Pericycle

Phloem

Endodermis

Cortex

Unicellular hair

Epidermis