Vascular bundle

Institute of botany, university of the punjab

1. Vascular bundle Define Vascular plant are also called “ Tracheophyta ” ( Trachaea =vessel a component of plant and phyta means =plant). Vascular bundle is divided into two components : xylem phloem

2. Xylem The term xylem was proposed by the Nageli (1858 ). He derived the word from a Greek word “ Xylos ” meaning wood ,The main function of xylem to conduct water and minerals from root to leaves. Xylem plays an essential ‘supporting’ role providing strength to tissues

3. Components of Xylem Tracheides Vessles Xylem fibres Xylem paranchyma Tracheides These are fundamental cells of xylem .These are elongated tube like cells with tapering ends . the cells are non living at their maturity and mature cells are empty without protoplast.

4. Patterns of secondary thickening in tracheids : (a). Annular thickening : ( b). Spiral thickening (helical thickening): ( c). Scalariform thickening (ladder like thickening ): . (d). Reticulate thickening (net-like thickening): ( e). Pitted thickening:

5. Types