have intercellular spaces and they take part in photosynthesis. b) Spongy parenchyma: It is found below the palisade parenchyma tissue. Cells are almost spherical or oval and are irregularly arranged. Cells have intercellular spaces.
It helps in gaseous exchange. ( iv) Vascular bundles: Vascular bundle are present in mid-rib and lateral veins. Vascular bundles are conjoint, collateral and closed. Each vascular bundle is surrounded by a sheath of Cuticle Palisade parenchyma Spongy parenchyma Lower epidermis Epidermal hair Stoma Bundle sheath Phloem Xylem Upper epidermis Figure .
Transverse section of Dicot leaf parenchymatous cells called bundle sheath . Each vascular bundle consists of xylem lying towards the upper epidermis and phloem towards the lower epidermis. . Internal Structure of Monocot Leaf (Isobilateral Leaf) Ex.Grass Leaf The transverse section of a monocot leaf reveals the following structures.
(i) Epidermis: Monocot leaf has upper and lower epidermis. Epidermis is made up of parenchyma cells. Cuticle is present on the outer wall stomata are present on both upper and lower epidermis. Some cells of upper epidermis are large and thin walled they are known as bulliform cells .
(ii) Mesophyll: It is the ground tissue that is present between both epidermal layers. Mesophyll is not differentiated into palisade and spongy parenchyma. The cells are irregularly arranged with inter-cellular spaces. These cells contain chloroplasts.
(iii) Vascular bundles: Large number of vascular bundles are present, some of which are small and some are large. . . Structure of Chloroplast Chloroplasts are green plastids containing green pigment called chlorophyll .
Chloroplasts are oval shaped organelles having a diameter of - micrometer and a thickness of - micrometer. Figure . Ultrastructure of Chloroplast Chloroplast DNA Starch granule Stroma Tylakoid Stroma lamella Inner membrane Outer membrane . Envelope: Chloroplast envelope has outer and inner membranes which is seperated by intermembrane space.
. Stroma: Matrix present inside to the membrane is called stroma. It contains DNA, S ribosomes and other molecules required for protein synthesis. .
Thylakoids: It consists of thylakoid membrane that encloses thylakoid lumen. Photosynthetic pigments are present in thylakoids. Thylakoids forms