Chemical Barriers
- Plants have a range of defence mechanisms to infections and infestations
- These can be split into chemical and physical defences
Chemical defences
- Plants have chemical adaptations to prevent herbivores from eating them
- Antiseptics or antimicrobial enzymes
- Chemical poisons to deter pests that might eat them
- Mechanisms to attract other insects as a biological control
- These same chemicals can sometimes be used to treat human diseases
- Chemicals with antimicrobial properties can be extracted for human use such as in antibiotics
- Herbal face creams can use plant extracts such as tea tree oil, mint and witch hazel to have an antibacterial effect
- The pain relief drug, aspirin, originated from the bark of willow trees
Physical Barriers
Physical defences
- Plants also have several physical adaptations which provide protection
- The cellulose cell wall not only provides support for the plant but also protection from microorganisms
- The waxy cuticle of the leaf and stems acts as a barrier to microbes from entering the plant. The only place that they can enter in the leaf is through the stomata
- Bark provides a tough layer around the stem of the plant to prevent pathogens from entering
- As deciduous trees lose leaves in the winter the infection can be taken with them
- Thorns or hairy stems also makes it more difficult for pests to access the plant tissue to feed
Plant Adaptions Table
