Watch out for poison ivy! What biology teacher has not issued that warning as he conducted a field trip? In spite of this warning and constant efforts to identify the plant, many teachers and students acquire cases of poisoning during spring field trips. Identification and avoidance are not enough. Too many people are affected inadvertently. The casual hiker, the child searching for a ball in the bushes, the lady holding her pet cat in her arms, the man standing in the smoke of burning brush,

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... d even the gav blade who defies the plant and says he is immune-all are likely to break out with those itching painful blisters. Too, there is the inevitable student who plucks a plant and says, "Teacher, what is this?" Poison ivy can be controlled if a real effort is made. The biology teacher is the logical one to lead the campaign for eradication of the pest from field trip areas, for poison ivy is likely to be found wherever he takes his class, whether it is to a forest preserve, the school forest, a city park, a roadside, a vacant lot, or the landscaped school grounds. This discussion is concerned with the common poison ivy (Rhus radicanls) which is found throughout the United States except on the West Coast, where it is replaced by the western poison oak (R. diversiloba). There are other poisonous species of Rhz,s, common in the eastern states, such as poison sumac