December 2011 - Mary Syrett

Tidewater's Most Irritating Plant

by

Mary Syrett

For instigating itches, blisters, rashes, and general discomfort, few plants in the Tidewater can compete with poison ivy. Although a fortunate few persons are immune to poison ivy’s deleterious effects, between 50 and 70 percent of the population experience physical reactions after coming in contact with the plant. The unpleasant results of a “brush” with poison ivy may last for days, weeks, or even months. Severe cases sometimes require hospitalization.
Poison ivy has been irritating people for a long time. In 1609, English adventurer Captain John Smith gave the plant its apt name. He thought that it resembled English ivy or Boston ivy in appearance but went on to observe that “the plant causes abominable itchynge.”
Poison ivy is a member of the Cashew family (Anacardiaccac). Many residents of the Tidewater have probably heard of three “poison” members of this family: poison ivy (Toxicodendron radicans), poison oak (Toxicodendron toxocarium), and poison sumac (Toxicodendron vernix). Only poison ivy is common here.
Poison ivy is the most widespread of the three plants. Found from the East Coast to the West Coast and from southern Canada to Mexico, it grows throughout the Tidewater and in every type of terrestrial habitat, including swamps, forests and fields. Poison ivy can grow in full sun, as well as in nearly full shade. Preferred habitats include forest edges and recently disturbed open fields, but you might find it in your flower garden or lawn, or along your driveway.
Poison ivy grows in various ways. As a ground cover, it spreads outward and creates a knee-high thicket of foliage. As a freestanding shrub, it can grow as tall as 10 feet, with one stem and a few side branches.
As a vine, poison ivy uses thin, brown aerial roots to attach itself to the sides of trees or other objects. In this form, poison ivy reaches its greatest size. It is not uncommon to find vines as thick as your arm growing up trees.
“Leaves of three, let them be.” This rhyme pertains to the identification of poison ivy and poison oak but does not hold true for poison sumac. However, people are far more likely to come into contact with poison ivy in the Tidewater than with poison sumac.
Poison ivy has compound leaves; that is, each leaf is made up of distinct parts called leaflets. There is one leaflet at the end of the leaf stalk and two leaflets opposite each other below the first. This is known as a trifoliate pattern. The two lower leaflets have very short stalks and are often shaped like mittens.
The shape, color, and texture of poison ivy leaflets vary. Poison ivy’s trademark leaf triads are reddish when they first appear in the spring, but turn green in the summer. Although the color of its berries is sometimes mentioned as a way of identifying the plant, this is not as reliable as leaf identification. Also, the berries appear at the end of the growing season – not at all helpful for identifying poison ivy in the spring.
In the eastern United States, another wild vine—Virginia creeper—is sometimes mistaken for poison ivy. However, Virginia creeper more often has five leaves to a branch rather than three, and its leaves are more toothed than those of poison ivy. Virginia creeper is not only harmless but makes for a beautiful fall foliage plant.
The second half of that last statement can also be made for poison ivy. The green of the plant’s leaves in summer yields to brilliant reds, yellows and oranges in the fall. Their autumn brilliance is due to pigments characteristic of the Cashew family.
Poison ivy fruits are clusters of tiny, pumpkinlike seeds with an off-white or pale yellow rind. The rind eventually dries out and flakes off. The fruits also contain the chemical irritant urushiol, but that does not stop birds from eating them. Typically, the seeds pass through avian digestive tracts unharmed, making birds agents for the dispersal of poison ivy seeds.
Urushiol is far more problematic for humans. Poison ivy rash is allergic contact dermatitis caused by the substance. (The word urushiol is derived from the Japanese word for lacquer.) Urushiol is a colorless or slightly yellow oil that oozes from any cut or crushed part of the plant, including both stem and leaves. Simply brushing against a plant may not cause a reaction. On the other hand, a person may develop dermatitis without ever coming into direct contact with poison ivy. Sticky and virtually invisible, urushiol can be carried on the fur of animals, garden tools, golf balls, or on any object that has come into contact with a broken plant. After exposure to air, urushiol turns brownish-black, making it easier to spot.
Urushiol is highly potent. It’s estimated that the amount needed to make 500 people itch would cover the head of a pin. The resin is stable and long lasting—it can stay active for as long as five years on a dead plant!
Once it touches human skin, urushiol begins to penetrate in a matter of minutes. Individuals who are highly sensitive to the chemical will experience a reaction in the form of a linear rash (sometimes resembling insect bites) within 12 to 48 hours. Blisters and severe itching will follow redness and swelling. After a few days, the blisters become crusted and begin to scale. The rash can affect any part of the body, but especially areas where the skin is thinner and more sensitive to ivy sap. Soles of the feet and palms of the hands are thicker and therefore less susceptible.
The severity of reaction varies from person to person and may also change from year to year for some people. Severe reactions include swelling in the throat, dizziness, a burning sensation, weakness, and breathing problems. If you experience extreme itching or the exposure involves the eyes, throat, lungs, or genitals, or if infection sets in, you should seek medical attention. And remember: you can have an allergic reaction to poison ivy even if you never leave your house. Anything or anybody that has come into contact with poison ivy can spread it. Agents for spreading urushiol include clothing, tools, sporting goods, and pets. (Strangely, pets themselves are not affected by urushiol.)
Contrary to popular belief, though, you cannot get a poison ivy rash from someone else’s rash or blisters. The liquid inside your blisters is not urushiol but fluids your body has produced in an attempt to prevent the worst effects of exposure. Still, breaking the blisters is not recommended because it could prevent healing and lead to infection or permanent scarring.
The best preventative for poison ivy is to avoid it. Don’t touch the plant or walk through it. Never grab leaves along a trail or fence. If you must walk through poison ivy, step on the plants with the sole of your shoe and always wear long pants.
The plant’s almost invisible oily resin sticks to most surfaces, and can even be carried in the wind or in smoke when it is burned. Standard barrier creams offer little protection against poison ivy. If you have had a brush with the plant, wash all exposed areas of your body with cold, running water as soon as you can reach a stream, lake or garden hose. If you do this within five minutes of exposure, the water will neutralize or deactivate the urushiol in the plant’s sap and keep it from spreading to other parts of the body. Soap is not necessary and may even spread the oil, although lye soap, if available, is good for removing poison ivy oil.
Jewelweed, which typically grows near poison ivy, may also offer relief, if applied in time. Three to five feet tall with oval, rounded leaves, jewelweed is most easily identified by its vaguely trumpet-shaped flowers, which hang from the plant like necklace pendants. The liquid inside the stem, when applied immediately, may prevent a rash or lessen its effects.
After returning home, wash all clothing outside with a garden hose before bringing it into the house, where resin can easily be transferred to rugs or furniture. Since urushiol can remain active for months, it is important to wash all camping, hiking, and hunting gear that may be carrying the resin.
If you come down with a rash, avoid scratching the blisters. Cool showers will help ease the itching, and over-the-counter preparations, such as calamine lotion, may help relieve mild rashes. Soaking in a tepid bath with an oatmeal or baking soda solution is recommended to dry oozing blisters.
A hot bath or shower often produces relief because heat releases histamine, the substance in the skin that causes intense itching. Therefore, a hot shower will more than likely cause intense itching as the histamine is being released. The heat should be gradually increased to the maximum tolerable and continued until the itching subsides. This process will deplete the cells of histamine, providing up to eight hours of relief from itching.
In severe cases, corticosteroid drugs can halt the reaction to urushiol if administered promptly. A physician may prescribe a steroid cream containing hydrocortisone to be applied to poison ivy lesions four to six times a day. An alternative is to use steroid pills for short periods of time.
The most effective way to kill young poison ivy plants is to pull them up by the root or to dig them up (of course, always wear sturdy gloves). The most effective time to remove poison ivy is from May through July. Dispose of dead plants by chopping into small pieces and burying them. Do not use poison ivy parts in mulch or compost. When removing poison ivy vines, sever the main stalk of the vine between four to six inches above ground.
Poison ivy can be controlled in lawns and pastures with Banvel or Crossbow. These chemicals should not be sprayed near or under sensitive trees, ornamentals, or garden species. Poison ivy can also be controlled with Roundup, but do not allow Roundup to come into contact with desirable plants, as they too will die.
There is a possibility we may experience rampant outbreaks of poison ivy more than ever before due to global warming. The greenhouse gas carbon dioxide is a major factor in promoting global warming. Increased carbon dioxide emissions are facilitating the flourishing of invasive nuisance plants around the globe, including poison ivy. Climate shifts also affect spread of the plant.
Removing poison ivy isn’t always necessary, especially if the plant grows where it won’t bother anyone. Even if poison ivy grows in an area where people could come in contact with it, a prominently displayed warning sign might be the most practical measure.
Although poison ivy causes many of us discomfort, the plant does have some merit. For example, many birds, including warblers, woodpeckers, bluebirds, vireos, sapsuckers, thrushes and quail eat poison ivy berries. Rabbits, deer, muskrats, and other animals eat the fruit, stems and leaves with no ill effects. Thick stands of poison ivy provide cover for small wildlife, and the plant’s ability to thrive in disturbed habitats makes it valuable in protecting soil from erosion.
Poison ivy doesn’t have to get under our skin. With a little practice and some preventive measures, we can easily identify and avoid the plant. Knowing its benefits, we can learn to coexist with poison ivy when fishing, hunting or engaging in other outdoor pursuits and even respect it as another fascinating aspect of the Tidewater’s natural beauty.

Mary Syrett is a freelance writer and an avid student of nature.