Difference Between Tracheids and Vessels

The key difference Between tracheids and vessels is that the tracheids lack end plates while vessels have perforated end plates.

Division Tracheophyta is a plant group that comprises of vascular plants. Vascular plants possess a well developed vascular system to transport nutrients, water and minerals throughout the plant body. Primarily plants have two types of vascular tissues namely xylem and phloem. These tissues serve as conducting tissues, performing as a conduit for the transfer of water and other nutrients from the roots to the leaves. Hence, xylem and phloem start from the leaves and extend up to the roots.

However, xylem and phloem differ from each other structurally and functionally; xylem tissues transport water and other minerals from the roots to the leaves. On the other hand, phloem transports foods from leaves to the roots and other parts of the plant. Also, both xylem and phloem contain different cell types. Among the cell types of the xylem, tracheids and vessels are two important cell types. Tracheids are elongated narrow cells while the vessels are elongated cylindrical wider cells.

CONTENTS

1. Overview and Key Difference
2. What are Tracheids
3. What are Vessels
4. Similarities Between Tracheids and Vessels
5. Side by Side Comparison – Tracheids vs Vessels in Tabular Form
6. Summary

What are Tracheids?

Tracheids are elongated tube-like cells that transport water and minerals from roots to leaves in all vascular plants. They are a kind of specialised cells in the xylem tissue. These calls have tapering ends. Also, they have a narrow lumen. Furthermore, tracheids are thin cells, but they have a very thick, lignified cell wall. When mature, protoplasts disappear from tracheids; hence, they become nonliving cells.

Furthermore, tracheids are more primitive to the vessel elements that are characteristic of angiosperms. Unlike vessels, tracheids lack end plates. Also, they are imperforated cells. Other than the transportation of water and minerals, tracheids provide mechanical support to the plants as well.

What are Vessels?

Vessels are a type of specialised and advanced cells of angiosperms that conduct water and minerals within the plants. They are wider and cylindrical in shape. Furthermore, they arrange one on the other in end to end fashion and make a tube-like structure to transport water efficiently. They have perforated end plates.

Also, they have a wider lumen. Compared to tracheids, their cell walls are less thickened. Similar to tracheids, when mature, they become nonliving cells and their protoplasts disappear from the cells.

What are the Similarities Between Tracheids and Vessels?

• Tracheids and vessels are two cell types of xylem.
• Both are non-living cells designed to conduct water and minerals within the plant.
• Also, both possess highly lignified thickened cell walls.
• Furthermore, both are tube-like elongated cells.
• They together make the tracheary elements.
• Both tracheids and vessels are highly specialized cells.
• They devoid protoplast when they mature.
• Both tracheids and vessels provide mechanical support to the plant.

What is the Difference Between Tracheids and Vessels?

One notable difference between tracheids and vessel is that tracheids have the ability to retain water as they can resist gravity while vessels cannot. This is because they (tracheids) happen to have a higher surface to volume ratio than vessel cells. Furthermore, trachieds lack perforated end plates while vessels have perforated end plates. This is a major difference between trachieds and vessels.

While Tracheids are found in all vascular plants, vessel cells are a characteristic of angiosperms. Moreover, Tracheids are single cells with openings on both ends (thus not called syncytes), while vessels form by the joining of many cells in different arrangements (thus are syncytes).Thus it is another difference between tracheids and vessels.

Summary – Tracheids vs Vessels

Both tracheids and vessels are responsible for the transportation of water and dissolved minerals within the plant body. Moreover, they are xylem elements. But tracheids and vessels differ from each other by certain features. Tracheids are elongated, thin, tube-like cells present in all vascular plants to conduct water. On the other hand, vessels are elongate, cylindrical, wider, tube-like cells present only in angiosperms.

Furthermore, tracheids are imperforated cells while vessels are perforated cells. Tracheids have a narrow lumen while vessels have a wider lumen. However, cell walls of tracheids are thicker than the cell walls of vessels. Most importantly, vessels have perforated end plates while tracheids lack end plates. All the above-mentioned facts summarise the difference between tracheids and vessels.

Reference:

1.“Tracheid.” NeuroImage, Academic Press. Available here 
2.Nature News, Nature Publishing Group. Available here 

Image Courtesy:

1.”Tracheid of oak (from Marshall Ward)”By Harry Marshall Ward (1854–1906) – Marshall Ward H. The Oak: A Popular Introduction to Forest-Botany. – London: Kegan Paul, Trench, Trübner and Co. Ltd., 1892. (Public Domain) via Commons Wikimedia  
2.”Hardwood Pores”By McKDandy at English Wikipedia, (CC BY 2.5) via Commons Wikimedia