Parenchyma tissues in Plants

Parenchyma, is a plant tissue which is typically composed of living cells that possess a thin wall, do not have a proper structure and hence are adaptable with differentiating functions. The cells share a location of many places throughout the plant body. Consisting of living cells, they take part in the several processes that take place in the plat body such as photosynthesis, food storage, secretion and other simultaneous activities of the plant. Parenchyma is one of three main types of tissue which form the ground or the fundamental tissue of the plant forming a group along with sclerenchyma and collenchyma.

Parenchyma, makes up the mesophyll containing chloroplast of the leaves and the cortex and the pith of the stems and the roots. It also forms the soft tissues of the fruits as well. Cells of this specific type are also a part of the Xylem and the Phloem as the transference of cells and also the bundle of sheaths that surround the vascular strands that are present within the plant body. Parenchyma may be present in form of a compact tissue or might be having large spaces in between the cells of this particular tissue.

Large portions of every single plant organ is occupied by the distribution of parenchyma. They have their occurrence in the pith, cortex and the pericycle of the roots and the stem. These cells are also found in the leaves of the mesophyll tissue. They even have been distributed in the fleshy part of the fruits and the endosperm of a particular seed. The innermost layer of the periderm phelloderm is also made up of the parenchyma cells.

Parenchyma cells have been distributed throughput the plant body. Procambium and cambium play the primary role in giving rise to the xylem and phloem parenchyma belonging to the primary and the secondary conducting tissues respectively. Phelloderm originates from a special type of substance known as the phellogen. While in the leaves, protoderm and the ground meristem play a hand in the development of the parrenchymatous epidermis and also the mesophyll respectively.

Parenchyma cells which grow in isolated culture media are generally spherical in shape. While, in the cell aggregates they are polygonal in shape since they are placed in contact with other kinds and shapes of cell. Polyhedral cells having fourteen sides are the most common, however cells with 12, 13 and 15 or 16 or fewer are found. The other common types of shapes are elongated, stellated or the inner wall being protruded.

The mature parenchyma tissues may have a much more compacted set without having any intracellular spaces. The tissues may also have loosely arranged cells paving the way for the development of intracellular spaces that have a presence between them. Parenchyma cells most commonly have the possession of primary walls. The storage of parenchyma cells of the endosperm in a phoenix as well as in Asparagus contain the possession of thick walls. The reason behind the thickness of the walls is due to the deposition of hemicellulose.

Commonly, parenchyma cells contain living protoplast with single or multiple vacuoles. They may also consists of leucoplasts and chloroplasts. Various carbohydrates, fatty and nitrogenous substances are carved out from the cell sap of the parenchyma cells. The parenchyma cells which have an existence in the bulb of the onions contains various other substances like amides, proteins, sugars, etcetera within their cell sap. The cotyledons of most of the leguminous plants consists of proteins and starch inside their parenchyma cells. Proteins and starch are also present inside the parenchyma of potato tuber. On the other hand, starch has its presence in the parenchyma of endosperm, tubers, fruits, xylem, cortex and phloem.

Functions of Parenchyma cells

• Living parenchyma cells provide the site for the metabolic activities.
• Chlorenchyma contains the cells which consists of chloroplastids and can take part in photosynthesis.
• Storage parenchyma has the provision of storage for different kinds of materials.
• Parenchyma cells which are present within the xylem and the phloem parenchyma are responsible for the movement of water and solute molecules.
• Parenchyma cells present within the air spaces in the aquatic plants help in aeration and gaseous exchanges.
• Meristematic parenchyma possesses the power to play a part within the cell division and hence helps in healing of the wounds and the regeneration of the cells.
• Transfer of cells provide a help in the short distance transport of the solute molecules.
• The seedlings and some of the hydrophytes gain the mechanical rigidity from the turgidity which the parenchyma cells possess.