ANATOMY OF DICOT LEAF!

The leaf blade is placed horizontally.

Upper surface is more strongly illuminated than lower. The anatomy is different on the two sides(upper and lower).

ADAXIAL EPIDERMIS(upper epidermis)
•single layered
•closely packed
•thick cuticle
•few or no stomata

ABAXIAL EPIDERMIS(lower epidermis)
•thin cuticle
•numerous stomata: a stomata leads to air cavity.
(Function: exchange of gases and transpiration)

MESOPHYLL TISSUE
consists of parisade parenchyma and spongy parenchyma
1) Parisade parenchyma: three layers of closely packed cylinderical cells.
2)Spongy parenchyma: oval and spherical cells in between inter-cellular spaces.
   *CHLOROPLAST is present along the walls of parisade and spongy parenchymatous cells in order to capture maximum light for photosynthesis.

VASCULAR BUNDLE
*each vein is a vascular bundle running through the mesophyll.
1)XYLEM
   •Towards the upper side
    •Contains vessels, tracheids, xylem parenchyma and xylem fibres
2)PHLOEM
  •towards the lower side
   •Contains seive tubes and   companion cells
(Patches of sclerenchyma is associated with xylem and phloem)

Vascular bundles are surrounded by layer of thin walled parenchyma called Border Parenchyma which forms the bundle sheath. Bundle sheath may show extensions towards upper and lower epidermis.

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.