1. Defense Mechanism In Plants

2. Introduction
• Plants need to protect themselves from various
threats. Hence, some plants have modified
parts that are used for defense.
• These defense mechanisms are used to protect
plants from herbivorous animals & insects &
also from insects laying eggs on the plant.

3. Types Of Defense Mechanisms
1.
2.
3.
4.
5.
6.
7.
Thorns
Spines
Prickles
Shrinkage
Milky Latex
Trichomes
Volatile Organic Compounds (VOC’s)

4. Thorns
• Thorns are
modified branches
or stems with a
sharpened point.
• Carissa bispinosa
is a plant that
possesses thorns as
a defense
mechanism.

5. Spines
• Spines are
modified leaves or
stipules.
• Spines modified
from leaves are
seen in Opuntia sp
• Spines modified
from stipules are
seen in Acacia
erioloba

6. Prickles
• Prickles are
modified
extensions from the
epidermis.
• Prickles arise
from either stem or
leaves.
•Prickles from stem
are seen in Rose.

7. Prickles
• Prickles from
leaves are seen in
Solanum
pyracanthum.

8. Shrinkage
• Shrinkage occurs
when cells lose
turgidity.
•Animals may be
scared of fastmoving plants &
hence don’t eat
plants that shrink.
•Shrinkage is seen
in Mimosa pudica.

9. Milky Latex
• Milky Latex is an
aqueous secretion
that is poisonous.
• Milky Latex is
seen in Euphorbia
pulcherrima &
Opium poppy.

10. Trichomes
• Trichomes are hairlike projections from
the epidermis.
• There are glandular
hairs & nonglandular hairs.
• Non-Glandular
hairs are nonpoisonous but cause
irritation. E.g.
Capsicum pubescens

11. Trichomes
• Glandular hairs
are poisonous.
• Glandular hairs
are seen in
Cannabis sp.

12. Volatile Organic
Compounds
(VOC’s)
• VOC’s are
chemical substances
produced by plants
that are used as a
defense mechanism.
• Geraniums produce
a chemical called
quisqualic acid that
paralyses insects
when they feed on
the plant.

13. Conclusion
• Hence, we have learnt that plants have a
variety of defense strategies, physical as well
as chemical defenses, that protect themselves
from enemies.
• Defense mechanisms are therefore needed by
plants to affect not just a single threat but
multiple threats.

14. Bibliography
Information acquired from:
• www.wikipedia.org, visited on 2nd August 2013
• www.geraniumsonline.com/trichomes, visited on
2nd August 2013
Images acquired from:
• www.wikipedia.org, visited on 2nd August 2013
• www.google.co.in, visited on 2nd August 2013

15. CREDITS
CHAITALI
KIRK
FINIL
VINIT
SONY
SHARON

16. Thank You