What is the shape of the mesophyll cells in a leaf?

Identify the internal structure of the plant organs shown in the image below.

Point out the differences in the anatomy of the leaf of peepal $(Ficus \text{ } religiosa)$ and maize $(Zea \text{ } mays)$. Describe the key anatomical differences.

$I.$ Sunflower seed
$II.$ $A$ wheat leaf
$III.$ Pea plant
$IV.$ Leaf blade of grass
Bulliform cells are present in which of the above plants?

Assertion :- Vascular bundles of dorsiventral leaves are dissimilar in size.
Reason :- The thickness of veins vary in dorsiventral leaves.

Bulliform cells are responsible for