Complex Permanent Tissues | Definition and Types
“A complex tissue can be defined as a collection of structurally dissimilar cells performing a common function or set of functions.”
The complex tissues are made up of more than one type of cells. These cells differ from one another in their form and structure; however, these cells work together as a unit.
Types of Complex Permanent Tissue
Two types of complex tissues are found in the plants
(i) Xylem: It is the chief water-conducting tissue of the plants. Xylem functions as a conducting tissue for water and minerals from the roots to the top of plants, i.e., to the stems and leaves.
Alongwith acting like a conducting tissue, xylem also provides the mechanical strength to the plant parts. Mechanical strength is the ability to tolerate stress, pulling forces, compressive forces etc. without breaking off or tearing off.
(ii) Phloem: It is a living tissue that carries food materials, (in particular, sucrose, a sugar), from the place it is available (source) to the places where it is needed (sink). It transports the organic materials, usually from leaves to other parts of the plants like roots, growing tips of stems and leaves, flowers, fruits etc. The food prepared in the leaves through the process of photosynthesis needs to be transported to each and every part of plant body, which is facilitated by this conducting tissue called phloem.