Poisonous Plants
...e are a few groups that do not contain poisonous species. Lacking groups include certain groups of fungi, algae, and mosses (Kingsbury 40). A theory of why these plants are not poisonous is because they are not in great danger of getting consumed in mass numbers by other organisms (Kingsbury 40). So why is there toxicity in plants? This is a question that has been pondered for many years. It is a very difficult to understand why plants are poisonous (Kingsbury 27). There are a number of theories, however. Many think that it is a point of natural selection. A plant that has toxicity is superior to a plant that does not have toxic abilities, because plants that are poisonous kill their predators (Kingsbury 27). This seems very simple, but the plant must be eaten by the animal, to poison the animal. In the process, the plant is being killed to kill its predators. In the mentioned theory, for the toxic plants to be superior, it must be assumed that animals can learn which plants are poisonous or not. There is evidence to prove that animals can acquire this plant discriminating ability (Kingsbury 27). Farmers and ranchers have experienced the effects of plant discrimination. Pastures that are full of poisonous plants are not a problem, until animals from different parts of the country are introduced to the pasture (Kingsbury 27). The new animals are poisoned because they have not been conditioned to avoid the native toxic plants. The animals familiar with the native plants have learned to avoid the poisonous plants (Kingsbury 27). This can explain why plants in a pasture are toxic, however pastures have not been around forever. In fact pasture are a very recent condition, unlike those under which plants originally evolved (Kingsbury 28). Considering wild animals feed selectively (a little of this, a little of that), wild animals are rarely killed by consuming too much of a poisonous plant. This is because the there is a time in which the animal feels the effects of the poison, before the fatal amount in obtained. The animal feels a stomachache like effect and stops eating, thus the poisoning is self-corrected by the animal (Kingsbury 28). It is thought that wild animals have the capacity to stray away from plants that often causes them this sort of discomfort (Kingsbury 28). However natural selection cannot expl...