Poison-Ivy, Poison-Oak and Poison Sumac

Part 1

Produced by Tom Cosmas compiled from images made available by The Internet Archive.

Transcriber Note

Text emphasis is denoted as: Italics and =Bold=.

POISON-ivy

POISON-oak

and

POISON sumac

IDENTIFICATION PRECAUTIONS ERADICATION

Farmers' Bulletin No. 1972

U. S. DEPARTMENT OF AGRICULTURE

POISON-IVY, poison-oak, and poison sumac remind most people of painful experiences to be avoided, yet many do not know any one of the offending plants or their equally poisonous relatives. Learning to recognize them on sight is relatively easy, especially by examining the distinctive identifying characters described in the pictures and legends of this bulletin. There is then a good chance to avoid them or, if one must work among them, to take preventive measures to escape poisoning.

These plants are very common throughout the United States. They are found in fields and woods, along fence rows, rock walls, and hedges, in lawns and gardens, and even sometimes vining on houses. Usually in any one locality it is necessary to be certain of the identity of only two or three of them. Maps show at a glance where they are likely to be found. Frequent observation and recognition of the plants as they are encountered almost daily is the best way to become poison-oak or poison-ivy conscious. Nonpoisonous sumacs are easily distinguished from the poisonous species by the seed heads and leaves.

The old proverb, "an ounce of prevention is worth a pound of cure," is good advice to everyone, particularly as regards ivy-poisoning. Previous escape is not proof of immunity when conditions are right, and after poisoning occurs there is no quick cure known. Some relief may be obtained and recovery hastened by use of some of the tested remedies. In case of severe poisoning a physician should be consulted.

Poison-ivy and other poisonous plants growing in grounds frequented by people should be eradicated. In some places this can be done by careful grubbing. In others weed-killing chemicals may be better and more certainly would avert poisoning for most of us.

This bulletin supersedes Farmers' Bulletin 1166, Poison Ivy and Poison Sumac and Their Eradication.

Washington, D. C. Issued August 1945

POISON-IVY, POISON-OAK, AND POISON SUMAC: IDENTIFICATION, PRECAUTIONS, ERADICATION

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

Page

A widespread menace to health 1 Forms of poison-ivy and poison-oak 2 Common poison-ivy 2 Oakleaf poison-ivy 9 Western poison-oak 9 Poison sumac 16 Confusion of poisonous and harmless sumacs 19 Introduced poisonous sumac and related species 21 Poisoning 21 Precautions against poisoning 22 Treatment for poisoning 23 Eradication of plants 25 Chemical weed killers 25 Eradication by mechanical means 25

A WIDESPREAD MENACE TO HEALTH

EVERY 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 country.

One or more kinds of poison-ivy--common poison-ivy, oakleaf poison-ivy, and western poison-oak--occur in abundance in almost every part of the United States. Poison sumac is of more limited distribution and occurs chiefly east of the Mississippi River, usually in swampy regions.

Poisoning by these plants is largely preventable. A knowledge sufficient to identify them in their various forms is easily gained by anyone who will make a study of pictures and general descriptions and train himself by a little diligent practice to observe the plants in his locality. It is important to become poison-oak or poison-ivy conscious. This can be accomplished only by learning to know the plants by repeated experience in observing them in their various forms. Persons who learn both to know and to avoid the plants can save themselves much inconvenience and discomfort. The simple means of learning to recognize them will pay big dividends. It is the first step to the prevention of poisoning and to the eradication of the pests from private grounds and public places.

The most effective method of prevention is to eradicate the plants, and wherever possible this should be done. They should not be allowed to grow in lawns or gardens, with ornamental shrubbery, or on houses. Communities should not countenance the growth of poison-ivy or poison-oak in school grounds, on public roadways, or in parks, especially those frequented by children. The cost of medical aid for one season in treating pupils using an ivy-infested schoolyard is likely to be more than that of eradicating the plants, to say nothing of the suffering and inconvenience they may cause.

FORMS OF POISON-IVY AND POISON-OAK

Poison-ivy and poison-oak are known by a number of local names, and several different kinds of plants are called by these names. The plants exhibit a good deal of variation throughout the United States, so much so that even technical botanists cannot agree on the number of species and names that should be applied to them. They grow in the form of (1) woody vines attached to trees or objects for support, (2) trailing shrubs mostly on the ground, or (3) erect woody shrubs entirely without support. They may flourish in the deep woods, where soil moisture is plentiful, or they may be found in very dry soil on the most exposed hillsides. The plants are most frequently abundant along old fence rows and edges of paths and roadways, and they ramble over rock walls and climb posts or trees to considerable heights. They often grow with other shrubs or vines in such ways as to escape notice.

Part 2

The leaf forms among plants or even on the same plant are as variable as the habit of growth; however, the leaves always consist of three leaflets. The old saying, "Leaflets three, let it be," is a reminder of this consistent leaf character but may lead to undue suspicion of some harmless plant. Only one three-parted leaf leads off from each node on the stem. The leaves never occur in pairs along the stem. The wide range in habit of growth of plants and leaf types may be noted from a glance at the several pictures of plants and leaves.

The flowers and fruit are always in clusters on slender stems that originate in the axis of the leaves along the side of the smaller branches. The fruits usually have a white, waxy appearance and ordinarily are not hairy, but may be so in some forms. The plants do not always flower and bear fruit. The white or cream-colored clusters of fruit, when they occur, are significant identifying characters, especially at the season after the leaves have fallen.

For convenience, these plants are discussed in this bulletin under three divisions: (1) Common poison-ivy, (2) oakleaf poison-ivy, and (3) Western poison-oak. A technical botanist would recognize many species of plants in what are included as the common poison-ivy, and anyone will recognize that various forms occur within this grouping.

COMMON POISON-IVY

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 the variations are sometimes given other botanical names. The common poison-ivy may be considered as a vine in its most typical growth habit.

Figure 1.--The shaded part shows the extensive area where some form of the common poison-ivy is likely to be found. Other forms also may occur in parts of the same region.

Figure 2.--Large poison-ivy vine growing on a tree for support. This is the usual form of the common poison-ivy in wooded areas.

Figure 3.--A, Common poison-ivy growing in a hedge and on a shade tree on the edge of a lawn. B, Typical vine, showing leaves and the roots that attach it to the tree.

The vining type most often occurs in wooded areas (fig. 2), where it depends upon trees for support. Vines often grow for many years, becoming several inches in diameter and quite woody. Slender vines may run along the ground, mixed with shrubbery, or take support from a large or small tree. That a plant growing along the edge of a lawn and into the shrubbery may be quite inconspicuous as compared with a vine climbing on a lawn tree is shown in figure 3. The vine readily develops roots when in contact with the ground or with any object that will support it. When the vines grow on trees these aerial roots attach the vine securely ( fig. 3. B). A rank growth of these roots often causes the vines on trees to have the general appearance of a "fuzzy" rope, which sometimes serves a good purpose for identification. The vines and roots apparently do not cause injury to the tree except where growth may be sufficient to cover the supporting plant and exclude sunlight or break the plant from excessive weight. The vining nature of the plant makes it well adapted to climbing over stone walls or on brick and stone houses.

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