What is the Anatomy of Dicot Leaves?
The cross-section of the lamina of the leaf exhibits the epidermis, mesophyll, and vascular system. The epidermis covers both the upper surface and the lower surface of the leaf and bears cuticles.
The lower surface of the leaf bears stomata. The tissue between the upper and lower epidermis is called mesophyll. In mesophyll, chloroplasts are present which are responsible for performing photosynthesis.
The mesophyll is composed of the palisade parenchyma and spongy parenchyma. As the name suggests, the palisade parenchyma is elongated cells arranged vertically and the spongy parenchyma is rounded cells arranged loosely, situated below the palisade parenchymatous cells. Numerous large spaces and air cavities are present between the parenchymatous cells.
The vascular system is composed of vascular bundles present in the veins and the midrib. The size of vascular bundles depends on the size of the veins. The vascular bundles are surrounded by a layer of thick-walled bundle sheath cells.
What is the Anatomy of Monocot Leaf:
The monocot leaf is similar to the dicot leaf in many ways, however, in the monocot leaf, the stomata are present on both the upper and lower surfaces of the epidermis. The mesophyll layer is not differentiated into palisade and spongy parenchyma. One of the characteristic features of monocot leaf is that certain cells of the upper layer of the epidermis present in the veins are modified into large empty colorless cells known as bulliform cells. In the presence of water, the bulliform cells in the leaf absorb water and become turgid, thus exposing the leaf surface. However, in the absence of water, the bulliform cells lose water thus resulting in the curling of leaves inwards to minimize the loss of water.
What is Secondary growth?
The increase in girth of the dicotyledonous plants is defined as secondary growth. Two lateral meristems involved in secondary growth are vascular cambium and cork cambium.