Describe some of the means by which a plant might defend itself, bearing in mind that it is 'sessile' (it cannot move around)?

The plant could have structural defence mechanisms such as 'thorns' or 'spines' which could cause damage to the mouth of herbivores so the plant is not eaten. It could also have 'stings' which are little hairs in the form of small tubes with a spherical tip on the top. When an animal brushes against the tip, the spherical tip breaks off and the tube penetrates the skin and causes an itchy irritant to be injected as a warning. An example of this is a stinging nettle.