Xylem and Phloem

Eukaryotic cells that vary in basic functions and structure are called Plant cells. They are the unit structural component of plants. Plant cells are photosynthetic in nature and prepare their own food from the available natural resources. The plant cell is composed of a cell wall, cell membrane, vesicles, ribosome, nucleus, cytoplasm, peroxisome, endoplasmic reticulum, Golgi vesicles, vacuoles and other basic elements. The organelles of the cell work in a union that results in the growth and development of plants. Nutrients supplied to every cell are required for the plant to aid photosynthesis. This transport of nutrition in plants is facilitated by the vascular system. The vascular system is composed of fibrous networks that carry nutrients from one point to another. This vascular system is classified into two types. They are Xylem and Phloem.

Xylem

• Definition

Xylem, which is a complex tissue, belongs to the vascular system of plants. Xylem plays a vital role in the transportation of water and minerals in dissolved form to different parts of the plant. This also provides support to the plant by forming a woody cover on the outer ring of the stem. It provides the nutrient in the upward direction from the root to other parts of the plant. 

• Components and functions

The Xylem cells are composed of four different types of cells. They are:

1. Tracheids: These are elongated cells that play an important role in water and mineral transportation. The cells receive mechanical support from the tracheids. It is a conductive and lignified cell called tracheary elements. They are dead cells. 
2. Vessels: It is known by multiple names like xylem vessels, trachea vessels, vessel elements or vessel members. Water conduction is facilitated in plants by vessel elements. It is present only in flowering plants and absent in non-flowering plants. Each element of the vessel is connected by a perforated plate.
3. Xylem parenchyma: It plays a key role in the storage of fats and carbohydrates. It is also involved in water passage. These are the only cells that are alive in the xylem. They are composed of thin cell walls and contain huge vacuoles, nucleus and protoplast. 
4. Xylem sclerenchyma: They are dead cells that are fibrous in nature. They lack protoplast. They lie between the tracheids and xylem vessels. These are narrow cells and are elongated. Their walls are composed of lignin. 

Phloem

• Definition

Phloem, which is also a complex tissue, belongs to the vascular system of plants. It transports organic compounds that are formed during photosynthesis to other parts of the plants. This transports the carbohydrates produced through the sieve elements. It plays a vital role in storing water, carbohydrates and proteins. It aids in nutrient transport in the downward direction. 

• Components and functions

The Phloem cells are composed of four different types of elements. They are:

1. Sieve tubes: They play a chief role in the transportation of nutrients. Enhancement in their specialisation has resulted in the loss of nuclei and other cell components. They are highly dependent on parenchyma cells for their function and activity. 
2. Companion cells: They are specialised parenchyma cells. They have a nucleus along with other cell organelles like ribosome, plastid and mitochondria. They are metabolically active and thus possess a large nucleus. 
3. Phloem parenchyma: These are also called transfer cells. They are present on the terminal ends of branches, veins of leaves and stems. They play a primary function in the transportation of food. They are the storehouse of latex, resin and mucilage. 
4. Phloem fibres: The fibres of the phloem are narrow, contain thick walls and are elongated. It is widely spread in both primary phloem and secondary phloem. Transportation of sugars is facilitated by this.

Difference between Xylem and Phloem

The below table gives a detailed description of the differences between Xylem and Phloem:

Conclusion

Xylem and Phloem play an integral part in the functioning and development of plants. They provide support to the plants, aid in the transportation of minerals to different parts of the plants, and store starch, fats and water within for usage.