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Difference between Xylem and Phloem

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Difference between Xylem and Phloem

We have often studied about various terms in our biology lectures that have made an impact on our minds. Biology is all about the human body and its systems. We have studied about various parts and systems of the human body like the digestive system, the nervous system, the muscular system, the endocrine system, etc. These systems combine together to make a human body. Apart from the human body, various tissues are found in the plants that are essential for carrying the process of photosynthesis. The main tissues in plants include the xylem and phloem. Now, you must be wondering as to what xylem and phloem are and what is the difference between the two terms.

Xylem vs Phloem

Well, xylem is defined as the material/ tissue found in the plant that is responsible for carrying the food and water from roots to its leaves and stems. On the other hand, phloem is considered as the tissue that carries various substances like sugar from leaves to the roots. Phloem helps in providing nutrients to the plants. Both xylem and phloem are vascular tissues. Now, what are vascular tissues? Well, vascular tissues help in the transportation of water, minerals, and other substances in plants from roots to leaves and vice-versa. Let us discuss the points of contrast between the xylem and phloem.

1. Xylem is a vascular tissue that carries the food and water from the roots to the leaves in a plant. On the other hand, phloem is also a vascular tissue that carries various substances like sugar from leaves to the roots of a plant.
2. There is an upward direction in the xylem as the nutrients are transferred from roots to leaves. The nutrients travel in the downward direction, i.e., from leaves to the roots.
3. Xylem is positioned at the central position of the vascular bundle. Phloem is positioned outside the vascular bundle.
4. The tissues are in the shape of a tube. There are no cross walls present in the xylem. The tissues are in the shape of a tube. Phloem tissues are long and have cross walls attached to them.
5. fibres present in the xylem are small in size. The fibres present in phloem are larger in size.
6. Xylem is found in stems, leaves, and roots. On the other hand, phloem is found in leaves and stems only.
7. Xylem comprises of dead cells. Phloem comprises of a nucleus and a cytoplasm.
8. Xylem is present in a large amount in plants. Phloem is present minimally in plants.
9. Xylem consists of the following elements:
  • Vessel elements
  • Parenchyma
  • Fibres
  • Tracheas
  • Xylem Sclerenchyma
Phloem comprises of the following elements:
  • Sieve Tube
  • Fibres
  • Intermediary Cells
  • Phloem Parenchyma
  • Companion Cells
10. Apart from food and water, several minerals and nutrients are transported with the help of the xylem to the aerial parts of a plant. Apart from sugar, various amino acids are transported to the growing parts like flowers and fruits.
11. The formation of vascular bundles takes place with the help of phloem. The formation of vascular bundles happens with the help of the xylem.
12. Xylem helps the plant in having mechanical strength. This results in the nourishment of the stem. The sugar and amino acids travel to various parts of the plant like leaves, roots, tubes, etc.
13. Xylem undertakes the function of photosynthesis and transpiration, and this is done by transporting food, water, and minerals. Phloem undertakes the function of transporting the proteins and several other substances like mRNAs.

So, these are the fundamental points of contrast among xylem and phloem. Xylem and phloem are essential parts of a plant that helps the plant in growing and strengthening. Now, one question arises here regarding the xylem, i.e., are the cells of the xylem dead? Well, as mentioned above, xylem is made up of several dead cells. The chain of dead cells is called vessel elements. No specialized structures are present in the xylem, and this is the reason that they are considered dead. On the other hand, the cells of phloem are alive because sugar and amino acids are transported now and then. Thus, the tissues in the phloem are considered to be living.

Well, it is interesting to note that the xylem is a very complex tissue as all the cells present in xylem are dead and hollow. The only living cell in the xylem is the parenchyma. Parenchyma works with the dead cell for transporting the food and water from roots to the leaves and stem of the plant. Now, you must be wondering as to what are the kind of plants that have xylem and phloem? Almost all the plants have both the xylem and phloem. But there are some exceptions. For instance, plants like algae and mosses do not contain xylem or phloem.

Xylem and phloem are complex tissues as they have many functions to perform like transportation, strengthening, supporting the plants, etc. One of the significant examples of xylem and phloem is the tree trunk. The innermost part of the trunk contains a xylem, i.e., the deepest piece of the wood is dead. On the other hand, the outermost part of the tree is alive. Between the innermost and the outermost parts, the layers of phloem are present. The phloem is the living tissue responsible for the growth of the plant. Well, talking about the difference and examples, let us now put discuss the types of xylem and phloem.

Types of Phloem:

  1. Companion Cells: Companion cells are defined as the specialized cells that are attached to the sieve tubes. Due to this association of cells with the sieve tubes, they are called companion cells.
  2. Phloem Fibres: Phloem fibres are the fibres that have no branches. These fibres are elongated and are known as blast fibres.
  3. Phloem Parenchyma: Living parenchyma cells are present in the phloem parenchyma. These cells are cylindrical in shape.
  4. Sieve tubes: Sieve tubes are defined as thin structured walls. These walls have cellulose. These tubes are long and are longitudinally positioned. Sieve tubes consist of a cytoplasm and a nucleus.

Types of Xylem:

  1. Tracheids: Tracheids are defined as the thinly structured cells that are associated together. All the tracheids run parallel to each other. These thin cells are responsible for the transportation of food and water from one cell to another.
  2. Vessel Element: Vessel elements are smaller in size but are attached to each other. The vessel elements contain perforation plates. These plates are responsible for the transportation of several substances between roots, stems, and leaves.

So, these are the significant kinds of xylem and phloem. Xylem and phloem are essential parts of a plant. The growth and strength of the plant depend upon the xylem and phloem. The major point of contrast between them is that the xylem comprises of dead cells while the phloem comprises of living cells. Thus, xylem and phloem are essential for the flowering and fruiting of a plant.

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