By Donald M. Crooks , principal horticulturist, Division of Tobacco, Medicinal, and Special Crops , and Leonard W. Kephart , senior agronomist, Division of Cereal Crops and Diseases, Bureau of Plant Industry, Soils and Agricultural Engineering, Agricultural Research Administration Contents...

E VERY year sees many adults, and especially children, accidentally poisoned from contact with plants that they did not know were harmful. Had the sufferers known how to detect poisonous plants they could have avoided them and escaped the painful experience of severe skin inflammations and water blisters. Very few persons have a sufficient degree of immunity to protect them from poisonous plants, and many do not recognize them in the various forms that they assume in different parts of the count

Some form of the common poison-ivy may be found in almost every part of the country but the extreme West. The shaded area on the map in figure 1 shows the extensive range where some form of poison-ivy is likely to be found. The plant is known by various local names—poison-ivy, threeleaf ivy, poison creeper, climbing sumac, poison-oak, markweed, piery, and mercury. The most widespread form is classified by botanists under the botanical name of Rhus radicans or varieties of it; however, many of th

Of the several kinds of poison-ivy, the oakleaf form occurring in the Eastern and Southern States is more distinctive than some other types. Some people know it as oakleaf ivy while others call it poison-oak, a name more commonly used for the western species discussed later. Botanists have not always agreed upon the scientific name to be applied to this form; however, they now use the name Rhus toxicodendron . Some botanists have used the Latin names R. quercifolia , while others used the name T

The western poison-oak ( Rhus diversiloba ) of the Pacific Coast States is usually known as poison-oak, but is occasionally referred to as poison-ivy or yeara. It is likely to be found in the region designated by shading in figure 12 , and from central Oregon northward through Washington may be growing intermixed with common poison-ivy. The term “poison-oak” is a misnomer, as this species is in no way related to the oak but is related to poison-ivy. Anyone familiar with either of these plants in

Because of the same general appearance of several common species of sumac and the poison sumac, considerable confusion has occurred as to which one is poisonous. Throughout most of the range where poison sumac grows, three other species are the only ones that are likely to be confused. These are the smooth sumac ( Rhus glabra ), staghorn sumac ( R. typhina ), and dwarf sumac ( R. copallina ). All the nonpoisonous species have red fruits that together form a distinctive terminal seed head, as sho

The small Japanese lacquer-tree, although uncommon in the United States, is an introduced species of sumac ( Rhus verniciflua ) that is quite similar to the native poison sumac. It is native to Japan and China and is the source of Japanese black lacquer. Cases of poisoning hare been traced to contact with lacquered articles. Because of its poisonous properties, this tree should never be planted. A native shrub or small tree called poison-wood, doctor gum, or coral sumac is commonly found in the

The most effective way to prevent poisoning from the plants is to avoid contact with them. If it is necessary to work among them, some measure of prevention can be gained by wearing protective clothing, but it is necessary to remember that the active poisonous principle can easily be transferred. Some protection also may be obtained in advance by the use of protective creams or lotions. They prevent the poison from touching the skin, or make the active principle easily removed, or neutralize it

[1] For a fuller description of treatments for poisoning see: United States Public Health Service, ivy and sumac poisoning. Pub. Health Rpts. Sup. 161 (rev.), 8 pp., 1943. For sale by the Superintendent of Documents, Government Printing Office, Washington 25, D. C. Price, 10 cents. There seems to be no absolute quick cure for ivy poisoning for all individuals, even though many studies have been made to devise effective remedies. Remedies may be helpful in removing the poisonous principle or rend

By using care poison-ivy can be destroyed with chemicals without danger of poisoning to the operator. Except in very heavy growth, one may stand at a distance from the plants and apply the herbicide without touching the leaves. Most chemicals are applied as a spray solution, and many sprayers can be equipped with extension nozzles 2 feet or more in length. The greatest danger of ivy poisoning occurs from careless handling of gloves, shoes, and clothing after finishing the work. Garments should b

Poison-ivy can be grubbed out by hand quite readily early in spring and late in fall. When the ground is soft after rains the roots come out in long pieces. Grubbing when the soil is dry and hard is almost futile, since the roots break off in the ground, leaving large pieces that later sprout vigorously. Eradication by grubbing is permanent if well done. Because of his close contact with the plants, the person doing the grubbing should have a high degree of immunity to ivy-poisoning. Many people