Nature's public enemies

To introduce this program on poisonous plants, Lynn Poole exhibits a quiver of poisonous blow gun arrows used by primitive Ecuadorian Indians. William A. Dayton, chief of the Division of Dendrology for the U.S. Forest Service, recounts the superstitions and myths about poisonous plants and notes allusions to them in the Bible and in Shakespeare's works. He shows sketches of two groups of particularly virulent plants: water hemlocks and amanitas mushrooms. Mr. Dayton says that there are more than 500 species of poisonous plants in the United States, and some cause the loss of 4% of livestock each year. Two such classes of plants are the alkaloids, which contain nitrogen, and the glycosides, which produce prussic acid. He shows photos of toxic plant specimens and their reactions when ingested by animals. Cattle are susceptible to larkspur and St. John's wort; sheep to pingue, lupine, horsebrush, and halogeton; horses to locoweed and death camas. Mr. Dayton recommends various ways of controlling poisonous plants. A film shows poison ivy identification, and a man displays the poison ivy blisters on his arm. Mr. Dayton concludes with a description of nettles, burrs, and poison ivy/oak/sumac.