War of the Plants

from their environment in many ways. There are two major features of plants that ensure their continuation as species. One of these relates to their physical attributes. Spinifex grass, a plant native to Australia, provides a notable example. Adapted to life in the hot, desert inland, spinifex has developed tightly rolled leaves which reduce the effects of drought stress. The hairs, or trichomes, which are found on the inner surface of the rolled-up spinifex leaf are believed to assist in minimising water loss. Trichomes also have defensive roles against predators. Many plants, such as the sunflower, have hairy leaves which are rough to the touch. When the plant is bitten by a grazing animal, the sensation is unpleasant on the tongue and the animal normally moves on to find more palatable food. B Some plants have taken physical defence a step further. The stinging nettle, for example, is covered in hollow hairs called trichomes. However, unlike the harmless hairs of the sunflower, these trichomes resemble miniature hypodermic syringes. An irritant chemical is stored at the base of the 'syringe'. If an animal touches it, a shot of the chemical is discharged through the 'needle' and into the skin of the animal. The…