Question

Draw a neat labelled diagram of T.S. of Isobilateral leaf and explain the different parts.

OR

With a neat labelled diagram, explain the transverse section of monocot leaf.

Answer 1

The T.S. of monocot leaf (Eg: Zee mays). The T.S. of monocot leaf shows three regions namely epidermis, mesophyll and vascular bundle.

(i) Epidermis:

There are two layers of epidermis namely upper and lower epidermis. Both the layers are composed of a single layer of parenchyma cells with deposition of the cuticle. There are openings in both the layers called stomata surrounded by guard cells. There are elongated cells on the upper epidermis called bulliform cells or motor cells, which help in rolling the leaf to check transpiration.

(ii) Mesophyll:

It is the tissue present between the two layers of the epidermis. It is composed of loosely arranged cells with lots of intercellular spaces. The cells have chloroplasts and are photosynthetic

(iii) Vascular bundles:

It is a conjoint, collateral and closed type with xylem facing upper epidermis and phloem facing the lower epidermis. There is no cambium between xylem and phloem. The vascular bundles are surrounded by bundle sheath of parenchyma cells.