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Lecture notes – dicot stem
Molecular & Cellular Biology
University of Central Lancashire
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Lecture notes – dicot stem
Dicot stem is the solid cylindrical axial part of a plant consisting of nodes and internodes giving rise to leaves, branches, and flowers.
The cactus stem is a modified dicot stem consisting of fleshy tissue for the storage of large quantities of water.
The epidermis is composed of thin-walled cells arranged in close contact with one another. Outside the epidermis is the hydrophobic cuticle which also helps in the prevention of water loss.
The monocot stem is differentiated into the epidermis, hypodermis, and ground substance in the transverse section.
The internal tissues of the dicot stem are arranged in concentric layers or rings.
The vascular bundles in the monocot stem are scattered irregularly throughout the ground tissue.
Secondary growth is not observed in the case of monocots.
Dicot stems exhibit secondary growth due to the presence of secondary vascular tissues and periderm formation.
Medulla and medullary rays are present in dicot stems.
The surface of the stem can be smooth to rough and knobby with sharp spines. Some stems might have leaf scars indicating the points where the leaves were attached to the stem.
The internal structure of the stem corresponds with the general internal structure of most monocots.
The stems consist of a single apical meristem which is responsible for the formation of new cells and the growth of the plant.
The oldest parts of the palm stem are strengthened by the deposition of lignin and cellulose on the cells by the xylem and phloem parenchyma.
The cortex is the most prominent region of the stem, which is composed of long-lived thin-walled parenchymal cells. Some of the cells of the cortex are specialized as mucilage cells and laticifers.
The inner region of the cortex consists of chlorophyll-containing cells that can carry out photosynthesis. The content of chlorophyll progressively becomes lower in the inner layers of the region.
The vascular bundles have more xylem bundles which are involved in the conduction of water throughout the plant body.
The xylem and phloem of the stem remain alive throughout the life of the plant which in some species can be hundreds of years.
The tissue of the hypodermis and epidermis of the stem is present outside the central cylinder of the stem, which is collectively called pseudobark.
Lecture notes – dicot stem
Module: Molecular & Cellular Biology
University: University of Central Lancashire
