Plant Chemical Defenses

Monarch larvae on milkweed leaf
Many of the plant compounds that are useful herbal remedies may be produced by the plants as a chemical defense. Some plants produce bitter compounds that are unpleasant for animals to eat. Others produce poisonous and neurotoxic chemicals for example many members of the tomato family have poisonous leaves. Other plants produce milky latex which coagulates in the insect stomach. Still for every plant that evolved a defense there is a an animal that evolved to be able to resist it. The monarch butterfly eats the poison milkweed plant making itself unappetizing to other predators.

Even the common dandelion produces a milky latex. Dandelion latex is non-irritating to humans and is being considered as a source of rubber for tires. Scientists in Europe are breeding dandelions that produce more latex as an alternative to rubber trees.

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