What are Xylem and Phloem?
Plants are classified based on many criteria, and one such classification is the presence or absence of a vascular system. Essentially, a vascular plant has specialized features that help it to absorb water and minerals from the soil. These include special tissues such as xylem and phloem.
Xylem and Phloem are two different types of vascular tissues which are mainly involved in the transportation process. These tissues form a vascular bundle and these work together as a unit. The movement of xylem is unidirectional, while, the movement of phloem is bidirectional.
Xylem is one of the important tissues of the vascular system of plants. The main activity of this tissue is to transport minerals and water from roots and carry them to other parts of the plants. It has two separate chambers tracheids and vessels for transporting minerals and water. The term xylem is derived from the Greek word – ξύλον (xylon), meaning wood.
Phloem is also important as the xylem tissues for the vascular system of plants. The main activity of this tissue is to transport nutrients and food from leaves to other growing parts of plants. The term phloem is derived from the Greek word – φλοιός (phloios), meaning bark.
Difference Between Xylem and Phloem
Following are the important differences between xylem and phloem:
|Xylem tissues are tubular shaped structure, with the absence of cross walls. This tissue resembles the shape of a star.||Phloem tissues are elongated, tubular shaped structures that include thin sieve tubes with walls.|
|Xylem occupies the centre of the vascular bundle.||Phloem is located on the outer side of the vascular bundle.|
|Xylem fibres are smaller.||Phloem fibres are larger.|
|They are present in leaves, stems, and roots.||They are present in leaves, roots, stems but transports and grow in fruits seeds and roots.|
|These tissues move in a Unidirectional. (only in one direction – upward direction)||These tissues move in a Bidirectional. (both the ways – up and down)|
|They live with hollow dead cells.||They live with cytoplasm without the nucleus.|
|The total amount of xylem tissue is more.||The total amount of phloem tissue is less.|
|It consists of tracheids, vessel elements, xylem parenchyma, xylem sclerenchyma and xylem fibres.||It consists of four elements: sieve tubes, companion cells, phloem fibres, bast fibres, intermediary cells and the phloem parenchyma.|
|Transports soluble mineral nutrients and water molecules from the roots to the aerial parts of the plant.||Transports food and other nutrients including sugar and amino acids from leaves to storage organs and growing parts of the plant.|
|Forms vascular bundles with phloem.||Forms vascular bundles with xylem.|
|Provides mechanical strength to plant and helps in strengthening of the stem.||Translocates the synthesized sugars by the photosynthetic areas of plants to storage organs like roots, bulbs, and tubers.|
|It is responsible for replacing the total amount of lost water molecules through transpiration and photosynthesis.||It is responsible for transporting proteins and mRNAs throughout the plant.|
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