August 10, 1915. 



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Poison Oak and Its Kindred 



Every woodsman is acquainted with poison oak or some of its 

 disreputable relations. There are few regions of the United States 

 which are not plagued with some member of the tribe. It may be 

 stated once for all that in spite of the common name by which 

 these j)lants are known, they are not oak, and no nearer kin to it 

 than to mahogany or sassafras. They are known by names other than 

 poison oak. In fact, they carry so many aliases that suspicion is 

 at once aroused that there is something shady about their reputa- 

 tions. Those known under a certain name in one region are called 

 something wholly different elsewhere. 



When stripped of all disguises and properly identified, it is found 

 that all of them are sumacs. No matter whether called poison ivy, 

 poison oak, poison elder, poison ^sh, poison vine or whatever else, 

 they are still sumac. Some creep on the ground; some spread by 

 underground branches ; some stand erect as shrubs ; some assume the 

 size and appearance of small trees; some climb trunks a hundred 

 feet high and dig their aerial roots into tlie wood, like the claws 

 of a centipede; but for all that, they are sumac, and brothers of 

 the sumacs that make old fields beautiful with brilliant red leaves 

 and berries in autumn. There are said to be black sheep in most fam- 

 ilies, and the sumac family has its full allotment. 



Names of the Sinner.s 



The most common names for these plants are poison oak, poison 

 ivy, and poison sumac. There are three distinct species, but the 

 names are confused. The sumac is distinct from the others, since it 

 is a small tree — very small usually; but the oak and the ivy are 

 vines, and though they may be easily distinguished if certain differ- 

 ences are observed, the names oak and ivy are applied indiscriminately 

 by most people. The real poison oak does not grow in the eastern 

 part of the United States. The eastern vine is the ivy. Botanists 

 distinguish the three poisonous sumacs clearly, and while even they 

 differ somewhat in names, they do not differ in the lines separating 

 the species. Following are the botanical and the common names 

 of the three plants: 



Poison sumac {Bhus vernix), called also poison elder, poison dog- 

 wood, swamp sumac, poison oak, poison ash, poisonwood, and thunder- 

 wood. This is a bush or tree ranging from five to twenty feet high, 

 and in diameter from one to six inches. It prefers swamps, and 

 ranges from New England to northern Minnesota, and southward to 

 Georgia and Texas. It has compound leaves like those of the common 

 sumac. The fruit is about the size of small wild grapes and hangs 

 in bunches. It is greenish yellow, and when quite ripe is silver 

 gray or white. The wood weighs twenty-seven pounds per cubic 

 foot, is soft, of yellowish color, and might be useful for small articles. 

 The sap that runs from wounds in the bark and wood can be made 

 into a beautiful glossy, black varnish, like that used in Japanese 

 lacquer work. 



Poison ivy {Ukus toxicodendron) is also called poison oak, poison 

 vine, climbing sumac, poison sumac, mercury, black mercury vine, 

 markweed, and picry. Its leaves are compound, three leaflets in a 

 bunch. They vary in form, but generally they are shaped much like 

 the leaves of box elder, with pretty deep sinuses. That point should 

 be borne in mind by those who want to distinguish it from poison 

 oak, the leaves of which have no deep sinuses. There is, however, a 

 species of poison ivy with smooth-edged leaves which otherwise are 

 shaped like those of Cottonwood — but always three in a group. 



Poison ivy assumes two forms. One is a vine which climbs the 

 tallest trees, particularly dead trees. It has thousands of aerial 

 rootlets that anchor it to the wood — somewhat like the rows of legs 

 of a "thousand -legged worm." It climbs cliffs, fences, and any- 

 thing else that comes handy. The only practical limit to the height 

 it will climb is the height of the object on which it climbs. The 

 other form of poison ivy stands erect two or three feet high, spread- 

 ing by means of underground roots, and forming thickets of consid- 

 erable size, particularly on dry and rather poor ground. 



Poison ivy ranges from Novia Scotia to Wisconsin, crosses the 



Rocky Mountains and reaches Utah, and extends southward to the 

 Gulf of Mexico. The leaves assume bright colors in Autumn, and 

 the fruit hangs like long, thin bunches of very small grapes — the 

 size of elder berries — and birds feed on it most of the winter. 



Poison oak (Ehus diversiloba) is the true poison oak, though, like 

 its relatives, it has several names. It is a Pacific coast species, and 

 is found among the dry foothills of the Sierra Nevada mountains in 

 California. It may range far enough eastward to meet poison ivy 

 in the plateau region west of the Rocky Moimtains. It is an erect 

 shrub, and does not possess the propensity for climbing that dis- 

 tinguishes poison ivy, but it resembles the form of that plant which 

 remains on the ground. Its leaves are shaped much like the section 

 of an egg cut lengthwise. They have very shallow lobes, or scarcely 

 any. They bear much resemblance to the leaves of one of the west- 

 ern live oaks (Quercus wislizeni) which is associated with it, and 

 this may account for the name poison oak so universally applied to 

 the shrub on the Pacific coast. The leaves are smaller and thicker 

 than those of poison ivy, but the telltale number three is always 

 present. 



The three foregoing are the poisonous plants which give much 

 trouble to persons who work in the woods or have occasion to go there. 

 The descriptions here given are not complete or wholly exact from the 

 standpoint of the botanist; but the chief differences between poison 

 ivy, poison sumac, and poison oak are pointed out. 

 Not Misnamed 

 There cannot be the least doubt of the poisonous nature of the 

 plants, but they vary in rank. Sumac is most poisonous, ivy next, and 

 oak least; but all are capable of doing much damage. The same 

 poison is believed to pervade all. It is known to chemists as taxi- 

 codendrol. It is a non-volatile oil and is found in all parts of the 

 plants, leaves, flowers, bark, wood, and fruit. It is in the dead leaves 

 and stems as well as in the living; but most people agree that there 

 is more danger of being poisoned by the plant about the time it is 

 coming in flower than earlier or later. 



It is important to bear in mind that the poisonous oil is non- 

 volatile, because a recognition of that fact helps to remove a num- 

 ber of erroneous opinions regarding the dangerousness of the plants. 

 The oil does not evaporate. It does not float away on the air, as 

 benzine does. It is not carried by the wind, as an odor is. It re- 

 mains in the plant and on its surface unless rain washes it off, or 

 it is brushed or scraped off by actual contact with some object. 

 How People Are Poisoned 

 Some people imagine that they have been poisoned without coming 

 in contact with the plant. It is claimed that some people are so 

 susceptible to the toxin of these plants that they are poisoned by 

 riding along a road if poison ivy is growing on a bordering fence. 

 Many reports of that kind have been made. There are persons who 

 claim to be so sensitive that their eyes are poisoned by ' ' simply 

 looking in the direction of poison oak. ' ' 



That is impossible. The persons who make these claims are doubt- 

 less sincere in their assertions, but they have been deceived. The 

 skin must come in actual contact with the plant, or with some object 

 that has been in actual contact, or there will be no poisoning. It 

 was once supposed that malaria, yellow fever, and many similar 

 microbe maladies were carried by the air; but it is now known that 

 those diseases cannot be transported or transmitted in that way. 

 Neither can the toxin from poison sumac and ivy. 



One person may be more susceptible to the poison than another, 

 and apparently an individual is more apt to be affected at one time 

 than another. It is claimed that after being poisoned several times, 

 the individual gradually becomes immune; but that is not always 

 true, because many persons are injured every time they come in con- 

 tact with the plants, and the effects never become less violent. 



Injuries may be slight or extremely severe. Death has been known 

 to result. A peculiar claim has been made that certain subjects 

 when once poisoned never wholly recover, but at periods, sometimes 

 a year apart, the symptoms return, without further contact with the 



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