Lecture 7 - Permanent Tissues PDF

Lecture 7 –permanent tissues BOT1131: Plant Anatomy 16.10.2024, 12 -1 PM Based on Functions There are four significant kinds of parenchymatous tissues, depending upon their function within the plant cells: 1. Chlorenchyma: It refers to the parenchymatous cell that possesses chloroplast. Thus, i...

Lecture 7 –permanent tissues BOT1131: Plant Anatomy 16.10.2024, 12 -1 PM Based on Functions There are four significant kinds of parenchymatous tissues, depending upon their function within the plant cells: 1. Chlorenchyma: It refers to the parenchymatous cell that possesses chloroplast. Thus, it assimilates the chlorophyll pigments and is termed “Assimilatory parenchyma”. In leaves, it differentiates into mesophyll cell that has two distinct parenchymatous cells (palisade and spongy). It is present in the mesophyll zone of the leaves, sepals and phyllodes. Function: Participates in photosynthesis. a single-layered epidermis. Based on Functions 2. Aerenchyma: It refers to the parenchymatous cell that comprises large air-filled intercellular spaces and is termed “Air storing parenchyma”. Aerenchyma cells are prevalently present in the roots, stems and leaves of hydrophytes. It comprises a few large-sized air cavities between the parenchymatous cells to perform various functions. Function: Participates in gaseous exchange and maintains the buoyancy of hydrophytes. Based on Functions 3. Prosenchyma: It refers to the parenchymatous tissue that possesses elongated cells with a thickened wall, pointed cells mostly with little or no protoplasm, and tissues specialized for conduction and support. The prosenchyma appears spindle-shaped with tapering ends. Function: Promotes rigidity to a plant. Based on Functions 4. Storage parenchyma: It refers to the parenchymatous tissue that contains large-sized vacuolated cells. It stores water, minerals, sugar, protein granules, oil droplets etc. The cell wall of storage parenchyma is generally thick because of hemicellulose deposition. Function: Helps in the storage of food. Based on Functions 5. Xylem parenchyma: This kind of parenchymatous cells possess a small size and a thick cell wall. Function: Facilitates water and mineral conduction. 6. Phloem parenchyma: This kind of parenchymatous cells have elongated cells and a thin cell wall. Function: Facilitates conduction of food prepared by the leaves. 7. Epidermis parenchyma: This kind of parenchymatous cells are elongated with zero intercellular space. Epidermis parenchyma possesses a cutinized cell wall or cuticle enclosing a single-layered epidermis. Function: Protects the plant in counter to environmental stress. Based on Shape and Arrangement There are two types of parenchymatous tissues, depending on the shape and arrangement: 1. Oval or loose parenchyma: Here, the parenchymatous cells appear irregular, loosely arranged, and oval-shaped with more intercellular space. It is present in the inner cortex of the stem. 2. Angular or intact parenchyma: They appear polygonal- shaped and have intact cell arrangement with small or no intercellular space. It is present in the outer cortex of the root.