Different types of plant cells

Parenchyma cellCollenchyma cell

Sclerenchyma cellPhloemXylem

Parenchyma cells are usually depicted as the typical plant cell because they are not very specialized. These cells synthesize and store organic products in the plant. Most of the plant's metabolism takes place in these cells.

Parenchyma Tissue

1) Photosynthesis2) Storage of air3) Storage of water and minerals4) Two types of parenchyma are there palisade

Parenchyma performs photosynthesis where the rate is very high because of high chlorophyll content and spongy parenchyma acts as a air storage.

Important points of Parenchyma Tissue

Vascular parenchyma is the parenchyma, which is found associated with the vascular tissues xylem and phloem. Accordingly, it is distinguished into xylem parenchyma and phloem parenchyma.

Medullary parenchyma is the parenchyma, which is found radially arranged in between the vascular bundles in the stem. It is meant for storage of reserve food.

Conjunctive parenchyma is the parenchyma, which occurs in the root system. It is specially meant for storage of water.

Armed parenchyma is the parenchyma, which is found in the epidermis of leaves in some gymnosperms. The cells have many spiny projections. It is defensive in function.

Types of Parenchyma Tissue

Chlorenchyma is the parenchyma in which the cells contain large number of chloroplasts. Chlorenchyma takes part in photosynthesis. It occurs in the leaves and other green parts of the plant body.

Prosenchyma is a type of parenchyma where cells are elongated with tapering ends.

Arenchyma is the parenchyma in which the cells enclose large intercellular spaces that are filled with air. Aeranchyma helps in buoyancy and respiration. It is characteristically found in aquatic floating plants.

Collenchyma cells have a support function in plants, particularly in young plants. These cells help to support plants while not restraining growth due to their lack of secondary walls and the absence of a hardening agent in their primary walls.

Collenchyma Tissue

Collenchyma tissues are mainly found under the epidermis in young stems in the large veins of leaves. The cells are composed of living, elongated cells running parallel to the length of organs that it is found in. Collenchyma cells have thick cellulose cell walls which thickened at the corners. 

Collenchyma serve as supporting and strengthening tissue,

Collenchyma with chloroplasts, photosynthesis takes place.

Important points of Collenchyma Tissue

Sclerenchyma cells also have a support function in plants but unlike Collenchyma cells, they have a hardening agent and are much more rigid.

Sclerenchyma Tissue

Most abundant cells in plants. Spherical cells which flatten at point of

contact. Alive at maturity; pliable, primary cell

walls. Large vacuoles for storage of starch, fats,

and tannins (denature proteins

Important points of Sclerenchyma

Tissue

Sclerenchyma Fibres

Types of Sclerenchyma

Phloem tissue consists of: conducting cells, generally called sieve.

Elements; parenchyma cells, including both specialized companion cells or albuminous cells and unspecialized cells; and supportive cells, such as fibres and sclereids

Phloem Tissue

Sieve tube members of phloem conduct organic nutrients such as sugar throughout the plant.

 Phloem is the living tissue that carries organic nutrients (known as photosynthate), in particular, sucrose,[1] a sugar, to all parts of the plant where needed.

Important points of Phloem Tissue

Sieve tubesCompanion cellsPhloem parenchyma andPhloem fibres

Different types of cellular elements of Phloem

Sieve tube represent the most active food containing elements in the phloem tissue. The sieve tubes are found arranged parallel to one another from one end of the plant body to another. Each sieve tube is formed by ht e series of hollow, cylinder cells called sieve tube cells arranged one above other. The sieve cells are separated from each other by horizontal perforated plates called sieve plates.

The Sieve Tubes

Companion cell are more or less spindle shaped cells associated with the sieve tubes. Each companion cell is found attached to any one lateral surface of sieve tube. The companion cell and neighboring sieve cell together represent a pair of sister cells. The companion cell has a granular cytoplasm, prominent nucleus and one or two small vacuoles. The nucleus of the companion cell is said to be capable of exerting its influence on the adjacent sieve cells.

The Companion Cells

Phloem parenchyma is represented by a group of living parenchyma cells that are found in between the sieve tubes. They were meant only for storage of organic food.

Phloem Parenchyma

Phloem fibres are represented by the dead Sclerenchyma fibres that are found in between the sieve tubes. They are meant only for providing mechanical support.

Phloem Fibres

Primary phloem Primary phloem is the phloem that is

formed during normal growth of plant body. It is formed in the both monocots and dicots. The primary phloem is further composed of protophloem and metaphloem. The sieve tubes and the companion tubes, which appear earlier during normal growth, represent protophloem, while metaphloem is represented by the sieve tubes and the companion cells that appear later.

Types of Phloem Tissue

Secondary phloem

Secondary phloem is phloem which formed during secondary growth. Secondary phloem is characteristic feature of only dicots. It is also known as bast. It is also of commercial importance since it yields bast fibers.

Comparison of Dicot leaf and Monocot leaf

The most distinctive xylem cells are the long tracheary elements that transport water. Tracheids and vessel elements are distinguished by their shape; vessel elements are shorter, and are connected together into long tubes that are called vessels.

Xylem Tissue

Xylem caries water and dissolved nutrients from the roots throughout the plant.

Xylem is the upward conduction of water while phloem is the upward and downward conduction of food and minerals

Important points of Xylem Tissue

Xylem tracheids Xylem tracheae Xylem fibers and Xylem parenchyma

Different types of cellular elements of xylem

They are found abundant in pteridophytes, Gymnosperms and primitive angiosperms, In these groups of plant, the trachieds represent the most active water conductingElements. In advance angiosperms, the Trachieds are found restricted to leaf marginAnd leaf tip.

The tracheids are elongated, dead cells, with tapering ends. They are characterized by the presence of a thick cell wall consisting of primary wall and a secondary wall primary wall is composed of cellulose where as the secondary wall is made up of lignin

Xylem Tracheids

They are commonly known as xylem vessels. They are the most active water conducting elements in all higher angiosperms. The tracheae are found arranged parallel to each other, extending from one end of the plant body to another.

The tracheae are long cylindrical dead cells. They are characterized by a thick cell wall consisting of a primary wall and a secondary wall. The primary wall is made up of cellulose where as the secondary wall is made up of lignin. There is a spacious lumen that extends throughout the length of the trachea.

Xylem Tracheae

They are represented by the dead Sclerenchyma fibers that are found in between the vessels and the tracheids. They are meant for providing mechanical support to the essential elements.

Xylem Fibres

This is the only living component in the xylem tissue. It is represented by groups of parenchyma cells that are found in between the vessels and the fibers. They are meant for storage of reserve food.

Xylem Parenchyma

Primary xylem Secondary xylem

Primary xylem is the xylem that is formed during normal growth. It is a derivative of primary meristem. It occurs in both monocots and dicots. In the primary xylem, two types of xylem vessels can be distinguished, namely protoxylem and metaxylem.

Types of Xylem

Secondary xylem is the xylem that is formed during secondary growth. It is derivative of secondary meristem. It is a characteristic feature of only dicots. Secondary xylem is commonly known as wood. It is of commercial importance since it is extensively used in the manufacturing of doors, windows and furniture.

Secondary Xylem

Comparison of Protoxylem and Metaxylem

Xylem and Phloem Diagram

Character Phloem Xylem

Function Transportation of food and nutrients from leaves to storage organs and growing parts of plant.

Water and mineral transport from roots to aerial parts of the plant.

Movement Bidirectional (Moves up or down the plant's stem from "source to sink")

Unidirectional (Moves up the plant's stem)

Occurrence Roots, stems and leaves Roots, stems and leaves

Additional Functions

Forms vascular bundles with xylem

Forms vascular bundles with phloem and gives mechanical strength to plant due to presence of lignified cells.

Structure Tubular with soft walled cells

Tubular with hard walled cells

Elements Sieve tubes, companion cells, phloem parenchyma, bast fibers, intermediary cells, two tube flow

Tracheids, vessel elements, xylem parenchyma, xylem Sclerenchyma

Nature of tissue Living tissue Non living tissue at maturity

Comparison of Phloem and Xylem