Sunday, 23 May 2021

Smaller vascular bundles lie in the middle of mesophyll

Smaller vascular bundles lie in the middle of mesophyll

A leaf having stomata on both the surfaces is called amphistomatic. Each stoma possesses two dumb-bell shaped guard cells with or without subsidiary cells. Functions : (i) Epidermis provides protection to the leaf interior. (ii) Its thickened cells and cuticle reduce the rate of surface transpiration. (iii) Protection from entry of pathogens. 

(iv) Exchange of gases with the help of stomata. (vi) Folding and unfolding of leaves with help of bulliform cells in response to changes in atmospheric humidity and change availability of water.

 In Mesophyll : chymatous ground tissue of the leaves. Mesophyll of isobilateral monocot leaves is undifferentiated. All the cells are similar. They It constitutes the chloren- are, generally, oval or rounded in outlines.

The enclose small intercellular spaces. intercellular spaces with are connected substomatal cavities, Mesophyll cells contain abundant chloroplasts; therefore, they are the seat of photosynthesis. 3) Vascular Strand : It consists of a number of parallel vascular bundles. Smaller vascular bundles lie in the middle of mesophyll. The Targer vascular bundles and their extensions occupy the whole area between the two leaf surfaces.

 Bundle sheath extensions are sclerenchymatous. Each vascular bundle is covered by a sheath of parenchyma cells having chloroplasts. A single bundle sheath occurs in panicoid grasses while double sheath occurs in festucoid grasses. It has phloem towards abaxial side and xylem towards adaxial side.The Phloem does not show distinction.

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