It's that time of the year again. The little bare sticks that have sat dormant all winter are about to produce a tiny canopy of little leaves at their tips. In a matter of weeks, these few little leaves will explode into a beautiful, lush, green carpet of ...POISON IVY!

Most of us know a little about poison ivy. We have either had the rash or know someone who has. We know that it's a trifoliate (has three leaflets) and most of us have learned the old adage, "leaves three, let it be." Still I have found that there is more misinformation, more disinformation and just out and out wrong information about this plant than any other I know of. This is even more so for poison oak and poison sumac. Perhaps this isn't our fault, though. Poison Ivy and its relatives are perplexingly variable species. I've seen poison ivy whose leaves had smooth edges. Other poison ivy leaves have toothed edges. Some are lobed. Some are smooth on one edge and have one notch on the opposite edge of the leaf. Some of the leaves grow to be only about two inches in length. I have also seen poison ivy with leaves as big as my hand. It is usually found having three leaflet combinations but can be found with five or even seven!

The first European to write about this plant was Captain John Smith in 1609. It was he who coined the name "Poison Ivy." Ever since then, there has been confusion regarding this plant and its cousins. Over two hundred years ago, plant taxonomists, starting with the grandfather of them all, Carl Linnaeus, lumped the poisonous ivys, oaks and sumac in with the other less-poisonous varieties of the Rhus genus. This misclassification has caused confusion everywhere, even in the Wild Basin. About thirty years ago, taxonomists decided to move the most poisonous varieties into their own genus, the Toxicodendrons ("Toxico" meaning poison and "dendron" meaning plant or tree). One of the main differences between the Toxicodendrons and the others of the Rhus genus is the fact that they have cream colored berries as opposed to the red berries of the Rhus family.

Today scientists divide the poison ivys and the poison oaks into two species each and poison sumac stands alone. Of these, Poison Sumac (Toxicodendron vernix) is the least of our worries in central Texas. It's not found here since it is a water loving swamp tree (dendritic). Growing from 6 to 20 feet in height, the Poison Sumac is found in the east from Quebec to Florida and westward along the coast to far east Texas between Shelby and Hardin counties. It has pinnately compound leaves with from 5 to 13 smooth leaflets per stalk. Like most plants it has many common names. It's also known as Poison Weed, Poison Wood, Poison Tree, Swamp or Varnish Sumac, Thunderwood, Poison Dogwood, Ash or Elder. Linnaeus originally placed this tree in the Rhus family, mistaking it for the Varnish Tree of China. It is also often mistaken for the Smooth Sumac, the Stag Horn Sumac, and our own Flame-Leaf Sumac. Like many of the look-alikes, Poison Sumac has tiny sweet smelling flowers in the spring and is brightly covered with lovely red and yellow leaves in the fall, but remember, only Poison Sumac has cream colored berries.

Poison Oak is divided into the Eastern and Western varieties. The Eastern Poison Oak (Toxicodendron toxicarium, changed in 1971 from T. pubescens) has the most "oak-looking" leaves of any of the species. It usually has multi-lobed leaves, no aerial roots on the stems, and fuzzy fruits and leaves. It loves sandy soils from southern New Jersey to Florida and extending west into Texas, Oklahoma and Kansas.

Western Poison Oak (Toxicodendron diversilobum, a name changed from T. lobata in 1905) is quite variable, as are most of the species in this family. Even its name, diversilobum, refers to its diverse forms. Generally the leaf is larger and rounder than the species found in central Texas. It is occasionally lobed, often with many scallops on the edge of the leaf. It also occasionally takes on a wrinkled appearance. Usually there are three leaflets but occasionally 5 leaflet forms are found. There are aerial roots extending from the main stem. Like its cousins, it's best viewed from afar and the view is lovely when it dons its spring colors.

Western Poison Oak probably causes more trouble than any of the other species. As California's most prevalent woody shrub, human infection seems inevitable. Rashes from run-ins with this and the other Toxicodendrons cause more workman's compensation claims for lumberjacks, park rangers and firefighters than any other source. Firefighters are especially at risk. Smoke from burning poison ivy is extremely toxic. It can cause lung infections and a rash all over one's body. Air and wind by themselves can't spread the poison. It's a contact dermatitis reaction. Only direct contact with the plant, fomite, or smoke can infect a person. This western variety is found strictly on the Pacific Coast from Southern British Columbia to Baha California. Its range is stopped by the deserts and the Sierra and Cascade Mountain ranges to the east and by the Pacific on the west. The western variety was discovered by the prolific botanist David Douglas (1799-1834) on Vancouver Island, Canada in 1830. (The Douglas Fir and Phrynosoma douglassi, the Short-horned Lizard, are named after him.) Early Spanish settlers from Mexico called it "yiedra," Spanish for ivy (from the Latin word, "hedra"). Soon "maligna" was added to the name, for this was truly an "evil weed."

Climbing (scandent) Poison Ivy (Toxicodendron radicans) is the most common variety of this family found in central Texas. ("Radicans" means "rooting" and refers to its aerial roots.) It reproduces by underground rhizomes. Its many aerial roots gives the vine great clinging power and the stems an almost fuzzy appearance. The vines grow almost straight up and do not twine around its support like most scandents. Climbing Poison Ivy can grow 10 to 20 feet high and occasionally completely envelop their support plant, thus taking on the appearance of a poison ivy "tree."

The flowers, which appear in June, are unisexual, five-petaled, greenish-white sweet smelling blossoms which form between the stem and the base of the axiallary petiole. The fruit (drupes) appear in July and are yellowish, spherical and about 1/4 inch in diameter. The leaves are glossy, bright green, alternate, compound (like the rest of the family) and are, naturally, highly variable in shape. They are usually trifoliates, having three leaflets, but there are occasionally 5 or 7 leaflet specimens. In central Texas, Poison Ivy is often mistaken for Strawberries, Dewberries, Box-Elder, Wafer-Ash, Boston Ivy, and the Virginia Creeper, which has 5 leaves.

This is the most wide-spread of the species. It's found in South Canada where the French-Canadians call it "herbe de la puce," or "herb of the flea," and "bois de shien" or "wood of the dog." It's found through out the eastern United States, as well as all over Mexico, Central America, Bermuda, the Bahamas, Taiwan, and Japan, where it's called "tsuta urushi" or "climbing lacquer vine." It also lives in western and central China where they know it as "tan chi" or the "climbing vine." In recent times it has been accidentally spread into parts of England, Continental Europe, Australia and South Africa. I won't go into what they call it.

Non-Climbing Poison Ivy (Toxicodendron rydbergii) was named after Per Axel Rydberg (1850-1931), an expert on Western flora. This plant was considered a sub-species until the turn of the century. It survives in the more northerly climates of Canada than T. radicans. It's found in much of the western U.S. East of the Cascades, it's seldom found south of the New England area, although there are a few isolated colonies on the tops of some Appalachian peaks. Some scientists think that these are remnant colonies isolated since the last ice age some 12,000 years ago. In the central states this species extends all the way down into the panhandle and trans-pecos regions of Texas. To add to the taxonomic confusion, it hybridizes with the climbing species.

When we talk about the reactions to these plants, I must first explain that they are as diverse as the leaflet variations. It is the urushiol (pronounced oo-roo-she-ol) resin, from oleoresin found in the sap, that causes contact dermatitis in humans. Urushiol is found in all parts of the plant but the hairs, wood cells, anthers and pollen. This is why honey made by bees who feed on poison ivy, isn't poisonous. Even though the urushiols often produce a profound reaction in humans, birds eat the berries and bears, cattle, deer, goats, hogs and horses eat the leaves and stems with no ill effects. It is perplexing to note that rabbits, squirrels and rodents eat the very berries that can so debilitate a human.

It was shown by Dr. Mitchell and Dr. Rook in 1979 that the initial exposure to urushiols does not produce a dermatitis reaction. It takes one or more exposures to develop sensitivity but in six days after any exposure a body can be sensitized. This means is that there are people like the teacher who used to show (off) for his students how he could stroke and even chew poison ivy leaves. I guess this was a sort of a, "do as I say, not as I do" lesson. He did this for several years until the year he ended up in the hospital. There is also a record of a lady dying from poison ivy. She was only exposed to the sap every year while washing her husband's hunting clothes. After several years she died due to a severe reaction resulting in a kidney shutdown (Michael Ellis, Jan. 1986). Responses are determined by the amount of urushiol exposure and the sensitivity of the individual.

Dr. William Epstein and Vera Byers developed a human sensitivity test. By putting a small drop of urushiol on the forearm, they found four levels of sensitivity. 10-25% of the people are non-sensitive. 25% are mildly sensitive. 25-30% of the population are moderately sensitive and 10- 20% of the people are severely sensitive. Urushiols are among the world's most potent external toxins. The amount of urushiol it takes to cause a reaction is measured in nanograms (one billionth of a gram). Most sensitive people react in the 100 nanogram range. Dr. Epstein has estimated that it would take only one ounce of urushiol to cause a rash on everyone on the earth! It's often said that Native Americans were immune to poison ivy but this seems doubtful when you read about all the treatments Indians used for their rashes.

When urushiols are exposed to the air, they quickly oxidize and turn a dark brown. This leads to a test for their presence. If a leaf is placed between two white sheets of paper and the leaf is crushed, the wet spots will turn brown in a matter of minutes.

If you have a strong reaction to one member of the Toxicodendrons you will probably be very allergic to the others in the family. Cashews, mangos, and pistachios are commonly eaten cousins of the Toxicodendrons. If you have a severe reaction to the Toxicodendrons this does not mean that you will be allergic to these foods, but if you are allergic to cashews, mangos or pistachios, beware of the poison ivys, oaks and sumacs! Your reaction could be severe.

When you are exposed to urushiols the reaction usually progresses in three stages. (1) A day or two after contact the infected area begins to itch and becomes red from the dilation of blood vessels. Swelling (lymph leaking from the blood vessels) also occurs. (2) Two days later, small blisters filled with lymph begin to appear. (3) Lastly large blisters burst and begin to ooze for about four days. Within 2 to 4 weeks they begin to heal as your lymphocytes and macrophages begin to destroy the damaged tissue. If you can refrain from scratching the healing begins. To keep from scratching is, of course, the hard part but it is very important. Secondary infections such as impetigo can occur. If a child is infected, the parent should immediately cut his nails. There is a large misconception that the ooze from the blisters is infectious. This seems not to be the case (Fisher 1973). Spreading seems to come from touching the original oils and from fomites, other agents, such as clothes, gloves, shovels, or even your dog.

Treatment for urushiol exposure should start as soon after exposure as possible. Urushiols can bind with the skin within 10 minutes (Fisher 1973). A quick rinse with rubbing alcohol or even Clorox (mixed one part Clorox to 9 parts water) should be followed by rinsing with cold water. (Warm water will spread the oils.) Rinse a bunch! Do not wipe with a rag as this will spread the oils. Rinse, rinse, rinse. The use of soaps is questionable because they only slightly break down the oil but they also remove the normal skin oils that protect you. Steroids do help stop the spread of the rash. As later symptoms appear, it seems that anything that will reduce the itching and cool the skin, helps. Cooling the skin reduces oozing, as cool vessels constrict and don't leak as much. Calamine lotion helps reduce the itch and absorbs the oils. Oral antihistamines help. Cortisone creams usually aren't strong enough in the beginning but will help block the itch about two weeks into the rash. Even oatmeal helps absorb the oozing.

As you might have guessed, there are a multitude of folk cures. Before I go into these, I must remind you that some of these "treatments" are only based on historical literature and have not been scientifically tested. There are people who are allergic to almost anything. In some cases, the individual may be more allergic to the treatment than to the poison so use caution if you try these. If there is a bad reaction, please see a doctor.

The most popular herbal remedy is Impatiens (Impatiens capensis), which are also known as jewelweed or touch-me-nots. Unfortunately, these are rare in Texas. Euell Gibbons (1966) used these to make a tea and even froze the tea for later use. You can also just split the stem and put the sap directly on the infected area. Impatiens and gum weed (Grindelia squarrosa) were found to be useful by Scooter Chetham. A tea made of Giant Ragweed (Ambrosia trigida) helped Delena Tul (1987). A tea made from prickly ash (Zanthoxylum hirsuttum) and horsemint (Monarda citriodora) helped dry and heal a poison ivy rash for Margaret White (interview 1997). These teas should be used fresh two or three times a day; and poured, rather than wiped, over the infected area. Dock (Rumex), Plantain (Plantago major) and even shoe polish (which contains the drying agents clay and zinc oxide) have been rumored to help. No treatment for the Toxicodendrons has been found to work all of the time (Mitchell and Rook, 1979). Try these, if you wish but use caution and good luck

A Field Guide to Wildflowers, Trees & Shrubs of Texas by Delena Tull and George Oxford Miller
Gulf Publishing Company 1991, ISBN 0-87719-195-6

A Practical Guide to Edible & Useful Plants by Delena Tull
Texas Monthly Press 1987, ISBN 0-87719-022-4

Know Your Poisonous Plants by Wilma Roverts James
Naturegraph Publishers 1973, ISBN 0-87961-0123

Native & Naturalized Woody Plants of Austin & the Hill Country by Brother Daniel Lynch
C.S.C. Acorn Press 1981, ISBN 0-938472-00-3

Poison Ivy, Poison Oak, Poison Sumac and Their Relatives, Pistachios, Mangoes, Cashews by Edward Frankel, Ph.D.
The Boxwood Press 1991, ISBN: 0-940168-18-9

Roadside Flowers of Texas by Mary M. Wills and Howard S. Irwin
University of Texas Press 1961, ISBN 0-292-77009-X

Texas Wildflowers by Campbell and Lynn Loughmiller
The University of Texas Press 1984, ISBN 0-292-78059-1

The Doctors Book of Home Remedies compiled by the editors of Prevention Magazine
Bantam Books 1991, ISBN 0-553-29156-4