Describe internal structure of maize leaf.

$\rightarrow$ The leaf of maize is flat and long. The cells produced in mid leaf are of same type. So structurally the leaf of maize is called Isobilateral leaf.

$\rightarrow$ The thin section of maize leaf is stained with safranin and viewed under microscope then following layers are seen in it $(1)$ Epidermis $(2)$ Mesophyll tissue $(3)$ Vascular bundles.

$(1)$ Epidermis : In leaf, two epidermis are seen.

$\rightarrow$ Upper Epidermis: It forms the upper most layer or adaxial layer. It is a single layered tissue made up of parenchymatous cells. Its outer surface is covered with protective layer of cuetile.

$\rightarrow$ In adaxial layer at some certain distance Bulliform cells are arranged in long rows. These cells are in group of $5$ to $7$ cells.

$\rightarrow$ These cells in group are comparatively larger than other cells of epidermis. They don't have protective skin on outer wall of them and it is very thin. Generally unicellular slanting small trichomes are located on both sides of the cells. These trichomes direct moisture in the atmosphere. So they are called moisture showing trichomes.

$\rightarrow$ The presence of bulliform cells separates adaxial layer from abaxial layer. Bulliform cells in humid atmosphere absorb water and become turgid and leaf surface is exposed. In dry atmosphere when they are flaccid due to water stress they make the leaves curl inwards to minimize water loss. Thus by these cells, the leaf curls from one side to other side these cells are called motor cells. Moisture absorbent or Bulliform cells are round and like a bubble so called bulliform cells.

$(2)$ Mesophyll Tissue : A leaf possesses isobilateral structure so there is no differentiation like palisade and spongy in mesophyll tissue.

$\rightarrow$ All cells are alike and possess equal amount of chloroplasts.

$\rightarrow$ Only palisade tissue is located between both epidermis in the leaf of maize. These cells are round or oval. Cells have inter cellular space. Air filled sacs are seen clearly below stomata. They are called respiratory cavities.

$(3)$ Vascular Bundles : Maize being a monocot plant, parallel venation in its leaf, vascular bundles are cut vertically. They are located at equal distance from each other.

$\rightarrow$ Vascular bundles are conjoint collateral and of closed type.

$\rightarrow$ Vascular bundles are of large and small both types. Vascular bundle xylem is located towards adaxial layer and phloem tissue is located towards abaxial layer.

$\rightarrow$ Vascular bundle is surrounded by sclerenchymatous bundle sheath. This bundle sheath is developed till adaxial and abaxial layer so vascular bundles provide strength to leaves.