Question

What are some examples of plant mechanical defences?

Answer 1

Hint: Plants are used as food by herbivores, both large and small, and they vigorously chew them. Plants have evolved a number of tactics to deter or destroy intruders, such as growing (modified)Thorns in the case of cactus.

Complete answer:
Plants have an intact and impenetrable barrier made up of bark and a waxy cuticle as their first line of protection. Both defend plants from herbivores. Strong shells, thorns (modified branches), and spines are some of the other adaptations toward herbivores (modified leaves). Animals are discouraged by causing physical harm or causing rashes and allergic reactions. Cactus spines, for example.
Mechanical defences function by deterring herbivores (bean eaters) from eating the plant in the first place, injuring herbivores that do bite, and/or slowing herbivores down so they consume less of the plant than they would otherwise. Thorns on the leaf or stem, tree bark, and trichomes or barbs on the leaf are examples of mechanical defences. In certain cases, a plant's seeds are protected by a tough shell (think of a coconut, a jackfruit or a pineapple). The waxy cuticles on the leaves of certain plants shield them from microorganisms and insects. Both of these mechanical defences keep anyone from eating the plant and deter them from doing so.
A few plants can use bugs to protect themselves. This method performs admirably. When a herbivore attacks, a few plants attract creepy crawlies by feeding them something they like (nectar or something similar) in order to drive the creature away. It's a mutualistic relationship.

Note:
Chemical defence - If the plant's first line of defence is compromised, it must rely on other defence mechanisms such as toxins and enzymes. Secondary metabolites are compounds that aren't directly derived from photosynthesis and aren't needed for plant growth and development or respiration. Herbivores are poisoned by alkaloids produced by the Datura plant, for example.