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
1. Tracheides
2. Vessles
3. Xylem fibres
4. 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