Friday 27 January 2017

ANATOMY OF DICOT STEM!

EPIDERMIS - Single layer of closely packed cells covered with cuticle. Multicellular epidermal hair called Trichomes are present.
HYPODERMIS- Few layers of collenchyma.
Below hypodermis is present few layers of parenchymatous cells.
ENDODERMIS- It is a baby layer of barrel shaped cells which contain starch grains and is also known as Starch Sheath.
PERICYCLE- this layer bears semi lunar patches of sclerenchyma with intervening masses of parenchyma.
VASCULAR BUNDLES- Conjoint, collateral, open. (These are arranged in a ring; ring arrangement of vascular bundles is a characteristic of DICOTS).
Phloem is present outside and xylem is present inside.
PHLOEM - contains seive tubes, companion cells, phloem parenchyma.
XYLEM - consist of vessels, tracheids, xylem parenchyma and xylem fibre. Xylem is endarch(metaxylem outside and protoxylem inside).
A band of thin walled cells called
Cambium is present in between phloem and xylem.
MEDULLARY RAYS - These are the radially elongated parenchyma present between vascular bundles.
PITH- contains parenchymatous cells.

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