Complex Permanent Tissues
Complex tissues are made of more than one type of cells. The complex tissue consists of more than one type of cells which work together as a unit. This tissue is also known as conducting tissue or vascular tissue as their main function is to transport water, mineral salts and food materials. The two types of complex permanent tissue are: Xylem or wood and Phloem or bast. Xylem and phloem together form vascular bundles (Watch Complex Permanent Tissues Video to learn more).
They are both conducting tissues and constitute a vascular bundle. Vascular or conductive tissue is a distinctive feature of the complex plants, one that has made possible their survival in the terrestrial environment. Xylem consists of tracheids, vessels, xylem parenchyma and xylem fibres. The cells have thick walls, and many of them are dead cells. Tracheids and vessels are tubular structures. This allows them to transport water and minerals vertically. The parenchyma stores food and helps in the sideways conduction of water.
Xylem is a vascular and mechanical tissue. In other words,it is a conducting tissue. Xylem is composed of cells of four different types:tracheids; vessels or tracheae; xylem parenchyma; xylem sclerenchyma. Except xylem parenchyma,all other xylem elements are dead and bounded by thick lignified walls. Of these four types of cells of xylem,most important cells are vessels. Vessels are very long tube-like structures formed by a row of cells placed end to end. Tracheids are elongated cells with tapering ends. They conduct water.
Like xylem,it contains tubes but has no mechanical function. Phloem is composed of following four elements or cells.1.sieve tubes; 2.companion cells; 3.phloem parenchyma and 4.phloem fibres. Except for phloem fibres,phloem cells are living cells.
Complex Permanent Tissues Video
Useful for CBSE, ICSE, NCERT & International Students
Grade : 9
Subject : Biology
Lesson : Tissues
Topic: Complex Permanent Tissues Video
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