Defense Mechanism In Plants

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.

Types Of Defense Mechanisms

1. Thorns2. Spines3. Prickles4. Shrinkage5. Milky Latex6. Trichomes7. Volatile Organic Compounds (VOC’s)

Thorns• Thorns are modified branches or stems with a sharpened point.

• Carissa bispinosa is a plant that possesses thorns as a defense mechanism.

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

Prickles• Prickles are modified extensions from the epidermis.

• Prickles arise from either stem or leaves.

•Prickles from stem are seen in Rose.

Prickles• Prickles from leaves are seen in Solanum pyracanthum.

Shrinkage• Shrinkage occurs when cells lose turgidity.

•Animals may be scared of fast-moving plants & hence don’t eat plants that shrink.

•Shrinkage is seen in Mimosa pudica.

Milky Latex

• Milky Latex is an aqueous secretion that is poisonous.

• Milky Latex is seen in Euphorbia pulcherrima & Opium poppy.

Trichomes• Trichomes are hair-like projections from the epidermis.

• There are glandular hairs & non-glandular hairs.

• Non-Glandular hairs are non-poisonous but cause irritation. E.g. Capsicum pubescens

Trichomes• Glandular hairs are poisonous.

• Glandular hairs are seen in Cannabis sp.

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.

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.

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

CREDITS

CHAITALIKIRKFINILVINITSONY

SHARON

Thank You