Monocotyledonous leaf

Monocotyledonous leaf (Isobilateral / Equifacial Leaf)

In monocot leaves, the internal structure of both upper and lower leaf surfaces look similar.

Epidermis

• The epidermis is composed of barrel shaped parenchyma cells.
• It bears cuticle and epidermal hairs.
• In grasses, the epidermal cells are impregnated with silica.
• In these plants, some cells are modified into large, empty, colorless and round shaped cells called bulliform cells or motor cells.
• These cells contracts during dry season resulting in the curling up of leaves.
• When the bulliform cells absorb water, they become turgid and leaves are exposed.
• During try season, these cells become flaccid and cause the leaves to curl up to prevent water loss.
• Stomata are present in both upper and lower surfaces.

Mesophyll

• The mesophyll is not differentiated into palisade or spongy layer.
• It is composed of large spongy cells with chloroplasts.
• The cells are isodiametric with intercellular spaces.

Vascular Bundles

• Due to parallel venation, the vascular bundles are of nearly same size in all veins, except in the midrib.
• The bundles are surrounded by a bundle sheath. It also contains chloroplasts.
• Xylem is seen on the upper side, and phloem is seen on the lower side.
• Xylem contains tracheary elements.
• Phloem consists of sieve tubes and companion cells.