Plants are multicellular eukaryotes that consist of several tissues to perform specialised functions. Vascular tissues are significant for carrying water, minerals, and food to varying parts of the plant. It is made up of two appropriate tissues such as xylem and phloem. Vascular plants can grow higher than other plants because of their rigidity. Water is the main solvent for plant nutrition, important for photosynthesis and transport of minerals, hormones, and other molecules. Higher plants have developed transportation systems for the conduction of water known as xylem. Xylem is wood in many plants that is an essential raw material for society. Xylem vessels, tracheids, xylem parenchyma, and xylem fibres are the structural components of xylem and these are collectively called tracheary elements.
Tracheid is a kind of specialised cell in the xylem tissue. It is a primitive, spindle-shaped, fluid conducting element of the xylem. It is a tubular cell with tapering ends in the xylem of a vascular plant.
Tracheids are long, elongated cells, dead empty cells without cellular contents.
They originate from a single cell.
The protoplast disappears when maturation, therefore, tracheids become non-living cells.
These are located one above the other in the xylem.
They do not have perforation plates.
They have thin primary cell walls and thick lignified secondary cell walls.
Water flows from one tracheid to another tracheid through bordered pit membranes.
Tracheids are predominantly found in gymnosperms and some angiosperms.
They are not strong and can break more easily.
They can transfer water in only one direction, therefore, it is less efficient.
It stores and conducts water and minerals from the roots to the several parts of the plant.
It also gives structural support to the plant.
It prevents the blocking by air cavities in vascular plants because it has a higher surface-to-volume ratio than vessels, and they hold water by adherence in the absence of the transpiration process.
Images coming soon
Vessels are long, cylindrical, non-living elements of the xylem, and these consist of vertical rows of single cells. It is also called xylem element or xylem members.
Xylem vessels are a chain of cells.
They are predominantly present in angiosperms such as fern, however, they are also found in a few gymnosperms such as Gnetum, Ephedra, and Welwitschia.
The protoplast disappears when maturation, therefore, xylem vessels become non-living cells.
They have a pit membrane that transports the water.
They are stronger than tracheids.
The cell walls are thickened due to the deposition of lignin.
They can transfer in all directions, therefore, it is highly efficient than tracheids.
The two ends of a vessel are perforated and a perforation plate has one or more holes.
It helps in the conduction of water and minerals from the root to various parts of the plant.
It also provides mechanical strength to the plants.
| Tracheids | Vessels |
|---|---|
| These originated from a single cell | These originated from a linear file of cells |
| They do not have perforation | They have perforation |
| They can hold the water as they resist the gravity | They have not able to hold the water as they resist the gravity |
| They consist of primary thin and secondary thick cell wall | They consist of thick cell wall |
| They help in preventing air embolism | They do not help in preventing air embolism |
| They are generally found in gymnosperms | They are generally found in angiosperms |
| They are laterally connected | They are connected from end to end |
| They consist of less number of pits | They consist of a large number of pits |
| These are less effective in water conduction because of the transport of water in only one direction | These are more effective in water conduction than tracheids because of the transport of water in all directions |
| They have a high surface-to-volume ratio | They have a low surface-to-volume ratio |
| They have a narrow lumen | They have a broad lumen |
A plant is composed of various tissues that are made up of several cells similar to humans. Water is essential for photosynthesis, and acts as a major solvent for plant nutrition. Vascular plants are higher than other plants because of their rigidity. Xylem is a tissue essential for the storage and long-distance transport of water and minerals within the plant. It is the primary component of wood and is highly useful for society. The tracheary elements are tracheids and xylem vessels. Tracheid is a primitive, tubular, fluid conducting cell in the xylem. It is mostly found in gymnosperms than angiosperms and the cell walls are thin. These are derived from single cells and imperforated. The Xylem vessel is a long, cylindrical cell and is arranged as a chain. These are perforated and have thick lignified cell walls. It is highly found in angiosperms.
Q1. Why are tracheids dead cells?
Ans. Tracheids are dead cells because the excessive secondary wall thickening consists of lignin. Therefore, the cell wall becomes hard and impermeable to water and other components for the metabolism in the cell.
Q2. How does xylem transport water?
Ans. Transpiration develops tension that pulls the water in the xylem of the plant from the root and moves the water in an upward direction.
Q3. What substances do xylem vessels carry?
Ans. Xylem tissues have specialised cells in mature plants that are called xylem vessels. Xylem can carry water, and minerals from the roots to transport stem and into leaves.
Q4.What are vascular tissue and vascular plants?
Ans.Vascular tissues are composed of xylem and phloem that form a central stele through the axis of the plant. They are present in vascular plants such as ferns, flowering plants, and non-flowering plants.
Q5. What is the importance of vascular tissue in plants?
Ans. Vascular tissue is the group of multiple cells present in vascular plants that facilitates photosynthesis, and transport of water, minerals, and sugars from the root to all parts of the plant.
Q6. Where are tracheids found?
Ans. Tracheids are predominantly present in the xylem of ancient plants such as seedless vascular plants including ferns, horsetails, and club mosses and some gymnosperms including pine, cypress, and cedar trees.
Q7. What is a secondary cell wall?
Ans. A secondary cell wall is a wall formed inner to the primary wall and is present in mature and highly specialised cells such as tracheids and xylem vessels. It is made up of cellulose, lignin, and hemicellulose.
Physics
Biology
Chemistry
Mathematics
Economics
Psychology
Environmental Science
Social Studies
Fashion Studies
English