The xylem is the vascular tissue that moves water and nutrients from roots to various parts of the plant such as shoot and leaves. Major components of xylem tissue include: xylem parenchyma, xylem fibers, xylem vessels and tracheids.
The tracheid is one of the two cell types of the tracheary elements, the other being the vessels. These two are the water conducting elements in vascular plants. Tracheid cells are tube-like with tapering ends. At maturity, it becomes one of the non-living components of the xylem. They are usually have an average length of between 5-6 mm. Tracheids have pits, which are concave depressions on the cell wall. They also have primary and secondary cell walls.
The primary function of tracheids in vascular plants is to conduct water and mineral salts, provide structural support and prevent air embolism. Tracheids are common in pteridophtytes and gymnosperms. In pteridophytes, tracheids are only water conducting elements whereas in gymnosperms, the wood is composed chiefly of tracheids.
The xylem vessel is the other cell types of tracheary elements. The vessel is made up of vessel members with common end walls that are partly or wholly dissolved. The end walls may have perforations. The presence of perforation plate is the main feature that differentiates between xylem vessels from tracheids.
Both xylem vessels and tracheids lose their protoplast at maturity and therefore become non-living components of the xylem eventually. They also forma secondary cell wall in between the primary cell wall and the plasma membrane that is lignified.
In this article, get to understand the underlying difference and similarities between tracheids and xylem vessels. The basis of comparison includes: Function, pits, water conduction efficiency, cell wall thickness, surface area to volume ratio, connection and air embolism among others.
What You Need To Know About Tracheids
- Tracheids are tubular cells in the xylem of vascular plants, involved in the conduction of water from the roots to the leaves.
- Tracheids are present in all vascular plants (Pteridophytes, and Gymnosperms).
- They (tracheids) consist of less number of large pits.
- Tracheids are not efficient in water conduction because their walls are not perforated.
- Tracheids contain polygonal cross sections.
- They contain thin cell walls.
- Tracheids consist of a high surface to volume ratio.
- They are laterally connected and contain tapering end walls.
- Tracheids prevent air embolism in plants due to its high adhesion force in the narrow tube.
- Tracheids originate from a single cell.
- They are more lignified and therefore have a narrow lumen.
- Tracheids are shorter cells (about 1 mm long)
- They are imperforated cells.
- Tracheids are usually considered to be primitive cells.
What You Need To Know About Vessels
- Vessels are elongated dead cells found in the xylem of flowering plants, consisting of perforated cell walls throughout which the water flows.
- Vessels are only found in Angiosperms.
- They (vessels) contain a large number of small pits.
- Vessels are efficient in conducting water due to presence of perforations.
- Vessels contain circular cross sections.
- They contain highly thickened cell walls.
- Vessels consist of a low surface to volume ratio.
- Vessels are connected by end to end. They also contain diagonal or transverse end walls.
- Vessels do not have any role in the prevention of air embolism in plants.
- Vessels originate from a longitudinal file of cells and joined into long continuous tubes.
- They are less lignified and therefore have a wide lumen.
- Vessels are longer cells (about 10 cm long).
- They are perforated cells.
- Vessels are normally considered as advanced type of cells.
Difference Between Tracheids And Vessels In Tabular Form
|BASIS OF COMPARISON||TRACHEIDS||VESSELS|
|Description||Tracheids are tubular cells in the xylem of vascular plants, involved in the conduction of water from the roots to the leaves.||Vessels are elongated dead cells found in the xylem of flowering plants, consisting of perforated cell walls throughout which the water flows.|
|Presence||They are present in all vascular plants (Pteridophytes, and Gymnosperms).||They are only found in Angiosperms.|
|Pits||They consist of less number of large pits.||They contain a large number of small pits.|
|Water Conduction Efficiency||They are not efficient in water conduction because their walls are not perforated.||They are efficient in conducting water due to presence of perforations.|
|Cross Sections||They contain polygonal cross sections.||They contain circular cross sections.|
|Cell Wall Thickness||They contain thin cell walls.||They contain highly thickened cell walls.|
|Surface To Volume Ratio.||They have a high surface to volume ratio.||They have a low surface to volume ratio.|
|Connection||They are laterally connected and contain tapering end walls.||They are connected by end to end. They also contain diagonal or transverse end walls.|
|Air Embolisms||They prevent air embolism in plants due to its high adhesion force in the narrow tube.||They do not have any role in the prevention of air embolism in plants.|
|Origin||They originate from a single cell.||They originate from a longitudinal file of cells and joined into long continuous tubes.|
|Lignification||They are more lignified and therefore have a narrow lumen.||They are less lignified and therefore have a wide lumen.|
|Diameter||They are shorter cells (about 1 mm long)||They are longer cells (about 10 cm long).|
|Cell Perforations||They are imperforated cells.||They are perforated cells.|
|Alternative Description||They are usually considered to be primitive cells.||They are normally considered as advanced type of cells.|
What Are Some Of The Similarities Between Tracheids And Vessels?
- Both tracheids and vessels are dead cells at maturity.
- They are both components of xylem.
- Both have pits on their lateral walls.
- Both are usually present in primary and secondary xylem.
- Both tracheids and vessels can transport water.
- Both tracheids and vessels posses secondary lignified cell wall.
You May Also Read:
- Difference Between Primary Xylem And Secondary Xylem
- Difference Between Metaxylem And Protoxylem
- Difference Between Companion Cells And Sieve Tubes
- Difference Between Phloem And Xylem Cells