Harmful plants are much more common than we realize. The term "harmful" includes plants which are externally poisonous, or damaging to the skin, as well as those which are poisonous when eaten. The amount of harm or discomfort caused by any of these plants varies with each individual. There are people who experience little or no discomfort and those who have very serious, even lifethreatening, reactions. Age may be a factor because immunity can break down with age. It may surprise you to learn that some very common decorative plants found in homes, offices, and shopping malls can be harmful. Even more surprising is the fact that some plants grown in our gardens as food can have very harmful parts.
POISON IVY (Rhus radicans) is the most commonly known externally poisonous plant. It is easily recognizable with leaves made up of three leaflets with ivorycolored berries. Poison ivy can vary in size from a plant less than six inches high to immense vines with leaflets as large as a hand. It can be found in dry rocky areas, pastures, and waste areas as well along stream banks and in the woodlands. The leaves, bark, and berries are all the harmful. Skin contact may result in inflammation and swelling with a rash of blisters. Symptoms may develop in just a few hours or up to several days after exposure depending on the individual.
A large ivy vine growing on Blennerhassett Island.
RHUBARB (Rheum rhaponticum) was introduced into this country from Siberia. It is a common perennial plant raised for food. Rhubarb grows in clumps with thick, fleshy, reddish stalks and large heart shaped leaves. The stalks are commonly used in jams, pies, and other desserts. The leaves, are very poisonous and have been known to cause death when eaten. Symptoms of poisoning can range from a burning sensation in the mouth and throat, severe stomach pain, nausea, vomiting, and diarrhea to difficulty in breathing, convulsions, coma, or even death. Liver and kidney damage are also possible.
IRISH POTATOES (Solanum tuberosum) originated in South America and are grown for food in gardens across North America and throughout Europe. It is the green parts of the plants that are harmful, especially the skin, sprouts, and eyes of "greened" potatoes. The greening occurs when the potatoes are exposed to sunlight at the soil's surface during growth or after harvesting. Symptoms may include stomach pain with constipation or diarrhea, drowsiness, weakness, breathing difficulties, or, very rarely, paralysis, and death. Children are more susceptible to these harmful effects than adults. Cooking in water tends to counter the poisonous effects of the greened potatoes. Skin contact with the plant during flowering has been known to cause dermatitis, or inflammation of the skin, in some people.
PHILODENDRONS (Philodendron spp.) are common decorative plants found in homes, offices, restaurants, and other public places. They can be climbing or trailing vines or large plants with cut or lobed heartshaped leaves. All parts of the plant may cause intense burning of the mouth and throat if chewed or eaten. The effects are rarely lifethreatening.
POINSETTIAS (Euphorbia pulcherrima) are common decorative plants found in homes, churches, malls, and other public places during the Christmas season. These plants are native to tropical areas of Mexico and Central America. All parts of the plant, when eaten, can produce symptoms of stomach upset within an hour. The most severe would be abdominal pain, diarrhea, and vomiting. In some cases, the poinsettia's milky sap coming into contact with the skin can cause irritation or blistering.
buckeye (Aesculis sp.) tree, which is a tree native to Greece and Albania, was introduced into this country as ornamental shade trees. The leaves are palmately compound with five to seven leaflets which are toothed. In the spring they produce many large erect flower clusters which may be red, yellowish, pale pink, or white. The fruit is green, rounded and sometimes spiny. It contains the shiny brown seeds we call "buckeyes." The leaves, shoots, bark, flowers, and, seeds are all considered poisonous. Abdominal pain usually occurs within an hour, followed by vomiting and diarrhea. Other symptoms may include loss of coordination, dilated pupils, excitability, paralysis and a reduced ability of the blood to clot. Surprising as it may seem, Native Americans sometimes used them as food after having thoroughly soaked and roasted them. (A native buckeye is shown for an illustration.)
MISTLETOE (Phoradendron flavescens) is more common in the southeastern states, and is used throughout the United States in Christmas decorations. Mistletoe is a parasite, which means it gets its energy from living on another plant. It forms a dense, bushy growth with leathery oblong leaves in opposite pairs. It produces severe digestive upset. Drinking tea made from the berries has been known to cause death. Children are more susceptible to the poisonous effects which have been known to cause failure of the cardiovascular system.
JACK-in-the-PULPIT (Arisaema triphyllum), sometimes known as Indian turnip, is an herbaceous perennial. It is native to the northeastern and central United States and southern Canada. The plant is usually a single flower beneath two compound leaves made up of three whorled leaflets. The flower may appear purplish green on a central spike in the middle of a hoodlike bract. This bract, or modified leaf, appears greenish purple inside with pale greenish stripes. Red, berrylike fruit develops as the plant matures. The leaves and the fleshy underground stems are considered poisonous and cause an intense burning and irritation of the mouth and throat. Eating a large quantity produces inflammation of the stomach and intestines. Boiling, heating, or thorough drying eliminates the poisonous effect. In a few susceptible people, contact may produce dermatitis.
RAGWEED (Ambrosia artemisiifolia.) is found throughout North America especially in the eastern and north central states. It can be found in cultivated fields, old meadows, or wastelands. This summer annual blooms August through October. The stalked leaves are alternate up to the upper part of the plant and opposite below. The leaves are 24 inches long and cut in many bluntly toothed or lobed segments. The greenish yellow flowerheads occur in clusters at the end of a stalk that is 16 inches long. The windborne pollen causes hayfever and dermatitis. h)0*0*0*
POKEWEED (Phytolacca americana) is a native perennial found in the eastern United States and southern Canada which blooms from July through September. It grows in pastures, open places in forests, and along the edges of forests. The fleshy, often purple-tinged stalk has many branches and can grow to nine feet in height. It has simple, alternately arranged leaves with smooth edges. These leaves are tapered at each end. Pokeweed flowers are greenish white or pinkish with five sepals and ten stamens but no petals. They grow in elongated clusters at the tips of branches. The plant produces shiny, round, dark purple berries. The roots are thought to be the most toxic part and have been mistaken for parsnip or horseradish. Many sources consider the entire plant toxic although people have used the berries in pies and the young shoots are cooked in two changes of water as early spring greens. In susceptible people, a burning feeling begins right after eating, then vomiting, diarrhea, and severe cramping. Sweating, salivation, and vision disturbances can occur. Death may be brought about by the weakening of the respiratory system. In early history, the root was used as a remedy for skin disease and rheumatism and the berries were used for ink.
Bibliography
Haragan, Patricia Dalton. Weeds of Kentucky and Adjacent States: A Field Guide. Lexington, KY: The University Press of Kentucky, 1991.
Kinghorn, A. Douglas, ed. Toxic Plants. New York: Columbia University Press, 1979.
Kingsbury, John M. Poisonous Plants of the United States and Canada. Englewood Cliffs, NJ: PrenticeHall, Inc., 1964.
Muenscher, Walter Conrad. Poisonous Plants of the United States. New York: The Macmillan Co., 1948.
Szczawinski, Adam F. and Nancy J. Turner. Common Poisonous Plants and Mushrooms of North America. Portland, OR: Timber Press, 1991.
Tampion, John. Dangerous Plants. New York: Universe Books, 1977
