ABSTRACT
Man's interest in poisonous plants probably predates recorded time. In some early civilizations, poisons derived from plants were used to make weapons more deadly, thus increasing their effectiveness in hunting and as a weapon of war. Plant substances such as marijuana, cocaine, opium, and tobacco have economic consequences associated with their use that far exceed any associated with poisonous plants. Poisonous plants cause substantial economic losses and hardships to livestock operators. Information has been gathered over the last 85 years concerning the various aspects of poisonous plants and their effects on domestic livestock. Ranchers are concerned because poisonous plants cost them money in increased death losses, reduced weight gains and reproductive efficiency, and decreased livestock values due to unthrifty animals. Many poisonous plant situations have the potential of putting ranchers out of business when a given set of circumstances occur to cause catastrophic losses.
