In respect of physiological and economic aspects, complex tissues are of great importance.
- Complex tissues perform the duty of conduction of raw food materials to leaves and prepared food materials to all the living cells.
- Beside preparation of food, water is necessary for various reactions. This water is conducted from root to stem through the complex tissue named xylem.
- Through xylem tissue, dissolved minerals along with water also pass upwardly.
- Water used in transpiration also moves to leaf through xylem tissue.
- Complex animal bodies demand connective tissues made up of organic and inorganic materials that provide support and structure.
- The most important economic crop in Bangladesh is jute fibre. Jute fibre is the secondary phloem or bast fibre.
- The wood we use, in the construction of houses, in making furniture, boat or musical instruments or as fuel, is the secondary xylem.