Xylem vs Phloem: Difference and Comparison

Plants are classed based on a variety of factors, one of which is the existence or absence of the vascular system.

Vascular plant, in general, has characteristics that aid in the absorption of water and nutrients from the soil. They are made up of specialized tissues such as the xylem and phloem.  

These are two types of vascular tissues that are primarily engaged in transportation. These tissues prefer to form a circulatory bundle and collaborate as a single unit.

Xylem moves in only one way, but phloem moves in both directions.  

Key Takeaways

1. Xylem is a vascular tissue transporting water and dissolved minerals from roots to other parts of a plant. In contrast, phloem transports sugars and other organic compounds from leaves to other plant parts.
2. Xylem consists of dead, hollow cells forming continuous tubes, whereas the phloem consists of living cells transporting nutrients through sieve tubes and companion cells.
3. Both the xylem and phloem are essential components of a plant’s vascular system, enabling efficient nutrient and water transport for growth and development.

Xylem vs Phloem  

Xylem are elongated cells called tracheids, responsible for transporting water and minerals from the roots to the leaves of the plant. Phloem is responsible for transporting organic compounds, such as sugars and amino acids, from the leaves to other parts of the plant, such as the roots and flowers.

The xylem cells are lengthy tracheary components important for water transfer. The form of rackets and aesthetic components is used to classify them.

Vessel components are shorter and are linked together in tubes known as vessels. The vascular bundles include the xylem. Non-Woody plants have these vascular bundles. It is also found in the secondary xylem.  

Phloem is the living tissue found in vascular plants that are in charge of transporting soluble organic substances. Translocation refers to the movement of sugar sucrose to a specific area of a plant.

The term phloem comes from the Greek word phloios, which means “bark.” Phloem is made up of sieve elements, which include conducting cells, parenchyma cells, companion cells, and supporter cells.   

Comparison Table

Parameters of Comparison	Xylem	Phloem
Definition	Tubular-shaped structured tissues along with the absence of cross walls.	Tubular-shaped and elongated structured tissue with the presence of walls with thin sieve tubes.
Location	Centre of the vascular bundle.	The outer side of the vascular bundle.
Size of Fiber	Smaller	Larger
Quantity of Tissues	More	Less
Movements	Unidirectional (upward direction)	Bidirectional (up and down)
Mechanical Support	Offers it	Does not offer it
Conducting cells	Dead	Living
Type of Cells	Dead cells with the exception of parenchyma	Contains living cells.
Consists of	Tracheid, xylem parenchyma, xylem fibers, and vessel elements.	Sieve tubes, bast fibers, phloem fibers, companion cells, intermediary cells, and the phloem parenchyma.

What is Xylem?  

The xylem cells prefer to create lengthy tubes that operate to transfer materials. Furthermore, xylem sap is a combination of water and nutrients that flows through the xylem cells.

Both of these chemicals are transported passively, without the need for any energy. Capillary action is a phenomenon that aids in the upward movement of xylem sap against the gravitational pull.

Furthermore, capillary action happens anytime the liquid attempts to rise higher due to surface tension. Furthermore, when water clings to the xylem cells, it aids in water transport.  

Different types of cells can be found in the Xylem. Tracheids are also long cells that aid in xylem sap movement while also providing structural support.

The vessel components, on the other hand, are significantly shorter and aid in water conduction. Furthermore, the xylem is made up of parenchyma, which is a tissue that comprises the plant’s softer portions largely.  

In a vascular plant, there are two types of transport systems: xylem and phloem. Xylem aids in the movement of water and nutrients from the root to the leaf. The term xylem is derived from the Greek word for wood.  

The main xylem is produced during the procambium’s growth. It consists of the metaxylem and protoxylem. The secondary xylem is created during the secondary growth of the vascular cambium.  

The xylem tracheary parts are made up of tracheid cells with vessel members that are frequently thin, hollow, and elongated.   

What is Phloem?  

Phloem assists in the transport of photoassimilates via the translocation mechanism, which is composed of sucrose and proteins. This sort of movement happens in the leaves as well as in other areas of the plant.  

An osmotic gradient develops because there is a larger concentration of organic molecules inside the cells. In addition, water is passively pulled out of the surrounding xylem.

High turgor pressure is generated, and sugar solution forms inside the phloem, causing important chemicals to travel across the plant.  

Parenchyma, sieve cells, sieve tubes, sclerenchyma, and companion cells are all components of the phloem structure. Furthermore, these components tend to collaborate to aid in the transport of carbohydrates and amino acids.

Conduction of this sort happens from the source to the sink tissues.  

Phloem is vascular tissue that distributes nutrients created by photosynthesis in the leaves and other parts of the plant. Sieve elements, phloem fibers, and phloem parenchyma cells are the three types of cells that make up phloem.

The major conduits through which food items pass in a vascular plant are sieve tubes, which seem to be a column of sieve tube cells.

Phloem parenchyma cells, also known as transfer cells and border parenchyma cells, are located in leaf veinlets at the tips of tiny branches and at the ends of sieve tubes, where they also play a role in food delivery.   

Main Differences Between Xylem and Phloem 

1. Xylem is a tubular-shaped tissue with no walls present and resembles the shape of a star, whereas phloem has an elongated structure with the presence of thin sieve tubes.  
2. The xylem is present at the center of a vascular bundle, and a phloem cell is present at the outer side.  
3. The size of fibers present in the xylem is smaller than the ones in the phloem.  
4. Xylem tissues are more than phloem tissues.  
5. Xylem has unidirectional movements while phloem has bidirectional movements.  
6. Xylem offers mechanical support while phloem doesn’t.  
7. Xylem has dead cells, whereas phloem consists of living cells.  
8. Xylem includes vessel elements, tracheid cells, xylem parenchyma, and fibers. Phloem includes phloem parenchyma and fibers, companion cells, intermediary cells, sieve tubes, and bast fibers.  

References  

1. https://www.sciencedirect.com/science/article/pii/S0065250408601099  
2. https://www.sciencedirect.com/science/article/pii/S0168192313001597  

Last Updated : 20 July, 2023