Mechanical plant defences

• Pathogens are disease-causing viruses, bacteria, fungi or protists which attack plants as well as animals.
• Plants have physical and chemical defences against pathogens.
• Plants have also evolved other defences from attack, often to avoid being eaten by herbivores.
• The Mimosa pudica plant is very special, it has evolved to close its leaves and then point its stems towards the ground when touched by an insect as it lands on it, making it difficult for the insect to feed on the leaves.
• Some plants have evolved the ability to mimic, the ability of some organisms to copy the appearance or behaviour of others.
• The passion flower vine has evolved small yellow spots on its leaves, these look like the eggs left behind by butterflies.
• Female butterflies are unable to tell the difference between these and real eggs, so they lay eggs on other leaves to avoid competition when they 'might' turn into caterpillars.
• The passion flower vine suffers less damage to its leaves from feeding caterpillars.