Every living organism in the world needs food, water, nutrients and minerals to survive. Similarly, plants also need food, water and nutrients to survive. Therefore, plants have a system to transport these elements to every part of it. They have specialized cells to conduct transportation in them.
A type of tissue present in plants responsible for the conduction of food and water is Xylem. Xylem tissues transport minerals and water to all parts of the plant with the help of tracheary elements. Treachery elements consist of vessel elements and tracheids.
Vessel Elements vs Tracheids
The main difference between tracheary elements vessels and tracheids is in the structure of the two. In vessels, there is a perforation present at the endplates which gives it a tube-like elongated structure while in tracheids there is no perforation due to the absence of the endplate, and vessels are made from a group of cells while tracheids are made from a single individual cell.
Vessels are the tissues present in angiosperms for the conduction of minerals and water. These are the tubular dead cells with thick walls. Vessels are highly developed tissues. Tracheids are present in all vascular plants to conduct minerals and water to every part of the plant. They are also a tube-like structure with thin walls but these are not as developed as vessels.
Comparison Table Between Vessel Elements and Tracheids
| Parameter of Comparison | Vessel Elements | Tracheids |
|---|---|---|
| Structure | Vessels have a tube-like structure, having a perforation present at the endplates that are either diagonal or transverse. | Tracheids also have a tube-like elongated structure but without perforation and tapering end walls. |
| Origin | Vessels are a bundle of cells that is, they originate with a bunch of cells packed together but the individual cells of vessels are smaller than that of tracheids. | Tracheids originate from a single individual cell. |
| Presence | Vessels are present in angiosperms only. | Tracheids are present in almost all the vascular plants such as Gymnosperms, Angiosperms and Pteridophytes. |
| Cell perforation | Vessels have a cell perforation present at the endplates. | There is no cell perforation present in tracheids. |
What are the Vessel Elements?
Vessel elements form the building block for the transportation of water in the plants. Vessels are a bundle of longitudinal cells packed together to form a tubular structure. One vessel is connected to the other vessel through the perforation at the endplates.
Vessels are present only in angiosperms, that is, in flowering plants. Vessels also provide strength to the plants. Vessels are broader and have thick walls. Vessels help in better condition due to the presence of the perforation at the endplates.
The cross-section in vessels is circular. They have a large number of small pits in them which are circular in shape. However, they have a low surface to volume ratio. The cell walls of the vessel are lignified. When the cells of a vessel reach maturity, they become dead, but then too they perform their function as they are protected by the surrounding cells.
The presence of vessels is important for flowering plants and it is said that it is a key innovation. The functions and features of vessels make them advanced tissue.
What are Tracheids?
Vascular plants contain elongated cells to serve in the transportation of water and minerals, these cells are known as Tracheids. They also provide support to the plants, especially to the softwoods. Tracheids are a single-celled structure with thin cell walls. The cells of tracheids are longer and narrower than vessel cells. Tracheids are connected to each other laterally.
All vascular plants such as angiosperms, gymnosperms and ferns contain tracheids. Tracheids don’t have perforation so they are not as efficient as vessels in transportation. Tracheids exert more adhesion force between tissues.
The cross-section in tracheids is polygonal. They have a small number of large pits. They also have a high surface to volume ratio; therefore, they tend to hold water against gravity during the absence of transpiration. In tracheids, when cells reach maturity, they become dead. They have secondary lignified cell walls. The ends of tracheids are pointed.
Tracheids are the primitive cells, they are not as advanced as vessels. They do the same work as vessels but less efficiently.
Main Differences Between Vessel Elements and Tracheids
- Vessels are tube-like structures present in the xylem of flower producing plants with a perforation at the endplates while tracheids are also the tube-like structures in the xylem of vascular plants without perforation.
- Vessel tissue consists of a number of cells, that Is, they are a bundle of cells closely packed together while tracheids are a single-celled tubular structure.
- The single cell of a vessel tissue is smaller than the cell of a tracheid.
- Vessels are present mainly in angiosperms or flower producing plants while tracheids are present in all vascular plants.
- In vessels, endplates contain perforation while in tracheids there is no perforation present.
- Vessels are more efficient than the tracheids due to the presence of a perforation.
- The cross-section in vessels is circular in shape while it is polygonal in tracheids.
- Vessels have a large number of small pits while tracheids have a small number of large pits.
- Vessels have thick cells in their wall while tracheids have thin wall cells.
- Vessels have a low surface to volume ratio while tracheids have a high surface to volume ratio.
- Vessels are known as advanced cells while tracheids are known as primitive cells.
Conclusion
Vessels and Tracheids are the parts of the same tissue xylem therefore they have some similarities too. These together form a part of the complex tissues. Both have the same functionality. They tend to become dead when they reach maturity.
References
- https://bsapubs.onlinelibrary.wiley.com/doi/abs/10.3732/ajb.89.2.185
- https://scholarship.claremont.edu/aliso/vol11/iss1/5/