Plant Anatomy, Botany presentation on secondary growth of roots

1. BY
PRANJAL DHAKA
2042

2. • Why we need secondary growth?
• Anatomy of dicot roots.
• Process of secondary growth.

3. • It increases the ability of
plants to absorb water and
facilitates transport of
water and minerals in bulk
quantities.
• Helps in mechanical
support and anchoring
when the tree grows big.

4. • Epiblema: Consists of the
outermost epidermal layer
with root hair arising from
it.
• Cortex: Thin layer of
parenchymatous layer.
Main function is storage.
• Endodermis: Barrel
shaped, rich in Starch and
have radial and tangential
thickenings called
casparian bands due to
lignin depositions.

5. • Pericycle: Made up of thin
walled parenchyma cells. It gives
rise to cork cambium, part of
vascular cambium and all lateral
roots.
• Vascular Strands: They are
alternate bands of xylem and
phloem. Protoxylem towards the
periphery and metaxylem
towards the center.
• Pith: Not very prominent. Bundle
of parenchymatous tissue.

7. • It is wavy in the
beginning unlike in
dicot stems.
• The cambial ring is
completely secondary
in origin.

9. • principle water-conducting
tissue
• combination of vessels and
tracheids
• primary xylem derived from
procambium
• secondary xylem formed by
vascular cambium
• wood made of accumulated
secondary xylem

10. • principle food-conducting tissue
in vascular plants, located
toward the outer part of roots
and stems
• carried out through sieve cells
and sieve-tube members
• some sieve areas (pores) have
larger pores called sieve plates
• each sieve-tube member
associated with companion cell

11. • Roots can also form the
exact kind of periderm
by the process of
seconary growth.
• The cork cambium cuts
off the phelloderm
inside of it, composed of
living parenchymatous
tissue.
• It cuts off phellem (cork)
on the outside of it.