Describe internal structure of Monocotyledonous root and differentiate between Dicot and Monocot root.


Monocot root consists of following parts

(1)        EPIBLEMA OR PILIFEROUS LAYER
This is single outermost layer with a number of unicellular root hairs.

(2)        CORTEX
This is many layered zone of rounded or oval cells with intercellular spaces between them.

(3)        ENDODERMIS
This is inner most layer of the cortex and forms a definite ring around the stele. Radial walls and often the inner walls of endodermis are considerably thickened. Cells of endodermis are barrel shaped.

(4)        PERICYCYLE
This is ring like layer lying interval to the endodermis. Its cells are very small and thin walled but contain abundant protoplasm.

(5)        CONJUCTIVE TISSUE
The parenchyma in between xylem and phloem bundles is known as conjuctive tissue.

(6)        PITH
The mass of parenchymatous cells in and around the centre is the pith. It is well developed in most monocotyledonous roots. In some cases the pith becomes thick walled and lignified.

(7)        VASCULAR BUNDLES
Xylem and phloem form an equal number of separate bundles and they are arranged in a ring.
The arrangement in radial bundles is numerous. It is only in exceptional cases that they are limited in number. Phloem bundle consists of sieve tubes, companion cells and phloem parenchyma. Xylem bundle consists of protoxylem which lies abutting on the pericycle and metaxylem towards the centre. Xylem is said to be exarch and its development is centripetal. Protoxylem consists of annular and spiral vessels and metaxylem of reticulate and pitted vessels.

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