Poisonous Plants By Barney Lipscomb WHAT IS A POISONOUS PLANT? In the broadest sense, a poisonous plant is any plant that is potentially harmful in any manner to humans or animals. It can be any plant that causes symptoms of toxicity and can be, but is not necessarily, fatal. Poisonous plants are categorized in broad areas based on the effects they cause: 1) Allergies, 2) non-allergenic dermatitis [skin irritation from direct or indirect contact], and 3) internal poisoning [from ingesting parts of a plant]. In addition, some authorities also include mechanical injury [from thorns, spines, stinging or irritating hairs, etc.]. TOXIC PLANT SUBSTANCES Plants are chemical factories. Literally thousands upon thousands of chemical compounds are produced by plants. Most are harmless, yet many are very useful to man and some are essential to plant and animal life. Technically, a poison is a substance that in suitable quantities has properties harmful or fatal to an organism when it is brought into contact with or absorbed by the organism. Toxin, a more specific term, is any of various poisonous substances that are specific products of the metabolic activities of living organisms (Gove 1993). In referring to such material in plants, the terms have been used synonymously in the text. Plants are considered poisonous because of toxic compounds they produce. Toxic plant substances belong mostly to a relatively few broad categories of compounds (Blackwell 1990), i.e. alkaloids, glycosides, proteinaceous compounds, organic acids, alcohols, resins and resinoids (including phenolics) and mineral toxins (non-organic compounds). It is the dose that makes the poison and not the simple presence of the chemical. The amount that may be toxic varies, as different individuals of the same species (man) may react differently to the toxic compounds. Depending on size, state of health and other factors, an individual may be less sensitive or more susceptible to poisoning by certain plants. Fortunately, most poisonous plants must be consumed in large quantities to be toxic. Which part or parts of a plant might be considered poisonous? This varies substantially from plant to plant. The plant part considered the most dangerous is generally learned species by species. In certain species, the entire plant is considered poisonous and in others, the leaves, stems, roots, seeds, etc. may be the most toxic. THE MOST COMMON CAUSE OF HUMAN POISONING Some plants are more dangerous than others and therein lies a major problem. The most common cause in a human poisoning is mis-identification by the consumer or someone in the entourage (spouse, parent, etc.) (Bruneton 1999). Correct identification is therefore the first line of defense. This is particularly important when children are around. According to Litovitz et al. (1992), analysis of the 1991 Toxic Exposure Surveillance System (TESS) data, from the American Association of Poison Control Centers, shows that plants were implicated 112,564 times (6.12% of the calls). Children under the age of 6 accounted for 83.3% of the accidents and children between the ages of 6 and 11 accounted for 7%. More recently, data for 1998 (Litovitz et al. 1999) show similar statistics, but there was an increase of 10,014. Plants (excluding mushrooms) were implicated 122,578 times (8.76% of the calls). The 1998 data broke out age categories differently from the 1991 data. Children under the age of 8 accounted for 69% of the accidents. Individuals from 8 to 19 years of age accounted for 15%. Over the age of 19 accounted 16%. Four deaths were recorded in 1998 from exposures to plants. The most recent data for 1999 (Litovitz et al. 2000), shows plants were fourth on the list of substances most frequently (113,864 cases, 5.2%) involved in human exposures, down from 1998. Three deaths were recorded in 1999 from exposure to plants (two from Jimsonweed, Datura stramonium; one from China-berry, Melia azedarach). Data from the TESS do not reflect whether a plant is wild or cultivated; Jimsonweed and China-berry are both introduced and naturalized, and cultivated in Texas. POISONOUS PLANTS Dangerous plants are all around us. They are found in all of the major kingdoms including those once included in the plant kingdom: Protista (unicellular including many algae), Monera (the bacteria), Fungi (molds, mushrooms, and the like), Plantae (non-vascular and vascular). With an estimated 260,000 known vascular plants, it’s inevitable that people will come in close contact with a poisonous plant at some point in their lives. Gardening is alive and well. It is the most popular hobby in America There are numerous cultivated plants with toxic/poisonous properties including house plants, landscape plants, food plants and plants in floral arrangements. According to Spoerke and Smolinske (1990), houseplants are commonly involved in exposures and vary somewhat from area to area. Members of the Araceae family, such as Dieffenbachia (dumbcane) and Philodendrons are always high on the lists. Table 1 (see below, at the end of this article) lists commonly cultivated and horticultural plants (home/garden/landscapes)—by no means complete—that are reported to be poisonous. In addition to the poisonous cultivated flora, there are a number of wild plants (native or naturalized) that are poisonous. In recent years, there has been an increasing interest in gardening particularly with native plants, and just because a plant is “native” does not automatically mean it is safe to garden with or be around. True estimates of the number of poisonous plants in the world are nonexistent. Kingsbury (1965) noted, in the Western Hemisphere, 700 species of plants are recorded to “have caused loss of life or serious illness in man or animals. There are 265 (12%) native or naturalized taxa recorded as poisonous in North Central Texas (Diggs et al. 1999). In her book, Edible and Useful Plants of Texas and the Southwest, Tull (1987:181-195; 231-308) includes an informative chapter that discusses many poisonous and harmful plants in Texas, including wild plants, ornamental houseplants and yard plants, and poisons in the garden. CONCLUSIONS In summary, everyone should know the names of plants in their homes, in the landscapes, and in the woods around their homes or unfamiliar areas such as parks. It is not enough to know their names, but you also need to know if the plant is dangerous. If you are unfamiliar with a plant’s constituents and their toxicology, knowing only the common name could potentially be dangerous, since common names may be used for different plants. In cases of suspected toxicity/poisoning by plant material or any other source, it is very important that the consumer, and/or any other party assisting, gather sufficient material (flowers, fruits, leaves, etc., maybe with gloves) of the plant in question. You should immediately call the Texas Poison Center Network at 1-800-poison-1 (1-800-764-7661) or indirectly via the emergency number 9-1-1. This is a state-wide 800 service available 24 hours a day. The consumer or someone in the support group will be asked to identify or describe the characteristics of the plant for identification. If the consumer is unable to make a positive identification or described the plant in insufficient detail for identification over the phone, they will need to take the plant material to a botanist (the regional Poison Center will suggest where you can get that assistance) for critical determination. Once the plant has been identified (Latin name) you will call the Poison Center and/or the attending physician to notify them of the identification. For more information on poisonous plants, there are a number of Internet Web sites. See Appendix below for a few sources on poisoning and poisonous plants. APPENDIX There are number of Web sites on poisonous plants. However, one should never rely on information from a site to critically identify plant material suspected in poisoning or used in any way for home treatment. It is very important that the consumer, and/or any other party assisting, gather sufficient material (flowers, fruits, leaves, etc., maybe with gloves) of the plant in question. You should immediately call the emergency number 9-1-1. American Association of Poison Control Centers. American Association of Poison Control Centers lists Poison Centers, which are operated 24 hours a day, 7 days a week, 365 days a year. They each have a medical director as well as pharmacists or nurses available for your emergency questions regarding poisoning episodes. The centers give emergency information and may refer you to a hospital or doctor’s office, but most poisonings can be treated at home. There is no charge for calling a Poison Control Center. <http://www.aapcc.org/> Centers are listed by state. Below are the centers for Texas. Centers with an asterisk (*) indicate certification by the American Association of Poison Control Centers. This indicates that the centers are open 24 hours a day and provide direct-dial or toll-free access, are supervised by a medical doctor, serve a large geographic area, and must have registered pharmacists or nurses available to answer questions from the public. Dallas North Texas Poison Center Texas Poison Network* Parkland Memorial Hospital 5201 Harry Hines Blvd., Box 37926 Dallas, TX 75235 Emergency:800-POISON-1 (800-764-7661) El Paso West Texas Regional Poison Center* Parkland Memorial Hospital 4815 Alameda Ave. El Paso, TX 79905 Emergency:800-POISON-1 (800-764-7661) Galveston South Texas Poison Center* University of Texas Medical Branch Trauma Center, Room 3-112 Galveston, TX 77555-1175 Emergency:800-POISON-1 (800-764-7661) Temple Central Texas Poison Center Scott and White Memorial Hospital 2401 South 31st St. Temple, TX 76508 Emergency:800-POISON-1 (800-764-7661) Cornell University. Poisonous Plants Home Page. This is a growing reference that includes plant images, pictures of affected animals and presentations concerning the botany, chemistry, toxicology, diagnosis and prevention of poisoning of animals by plants and other natural flora (fungi, etc.). <http://www.ansci.cornell.edu/plants/> Canadian Poisonous Plants Information System. <http://sis.agr.gc.ca/pls/pp/poison?p_x=px> U.S. Food & Drug Administration, Center for Food Safety & Applied Nutrition, Office of Plant and Dairy Foods and Beverages, Poisonous Plant Database. The Poisonous Plant Database is a set of working files of scientific information about the animal and human toxicology of vascular plants of the world. The initial files were created in 1994, and are updated periodically. <http://vm.cfsan.fda.gov/~djw/readme.html> Poisonous Plants and Animals. This web site contains valuable information on poisonous plants and animals. A wide range of species are described and classified according to their habitat and biological origin. Special attention is given to the behavior of venomous snakes and insects with advice on how to avoid a deadly bite. The site also reviews the application of some plant and animal poisons in medicine and pharmacy thus showing that dangerous substances can sometimes be useful. <http://library.thinkquest.org/C007974/1_1hen.htm> REFERENCES (others included that are not cited in text) Blackwell, W.H. Poisonous and medicinal plants. Englewood Cliffs, NJ: Prentice Hall, 1990. Bruneton, J. Toxic plants dangerous to humans and animals. Translated by Caroline K. Hatton. Paris, France: Editions Technique & Documentation, 1999. Burlage, H.M. Index of plants of Texas with reputed medicinal and poisonous properties. Austin, TX: Published by the author, 1968. Diggs, G.M. Jr., B. Lipscomb, and R.J. O’Kennon. Shinners & Mahler’s illustrated flora of North Central Texas. Sida, Bot. Misc. 16 (1999). Fuller, T.C. and E. McClintock. Poisonous plants of California. Berkeley: Univ. of California Press, 1986. Gove, P.B., ed. Webster’s third new international dictionary of the English language unabridged. Springfield, MA: Merriam-Webster Inc., 1993. Hardin, J.W. and C.F. Brownie. Plants poisonous to livestock and pets in North Carolina. Raleigh: North Carolina Agricultural Research Service, North Carolina State Univ., Bull. No. 414(1993 revised). Hardin, J.W. and J.M. Arena. Human poisoning from native and cultivated plants, 2nd ed. Durham, NC: Duke Univ. Press, 1974. Hunt Institute for Botanical Documentation. Common Poisonous Plants. Pittsburgh, PA: Hunt Institute for Botanical Documentation, Carnegie Mellon University. n.d. James, L.F. and S.L. Welsh. "Poisonous plants of North America." In Poisonous plants: Proceedings of the third international symposium. Eds. L.F. James, R.F. Keeler, E.M. Bailey, Jr., P.R. Cheeke, and M.P. Hegarty. Ames: Iowa State Univ. Press, Ames, 1992. Pp. 94–104. Kingsbury, J.M. Poisonous plants of the United States and Canada. Englewood Cliffs, NJ: Prentice-Hall, 1964. Kingsbury, J.M. Deadly harvest: A guide to common poisonous plants. New York: Holt, Rinehart and Winston, 1965. Lampe, K.E. and M.A. McCann. AMA handbook of poisonous and injurious plants. Chicago: American Medical Association, 1985. Litovitz, T.L., K.C. Holm, K.M. Bailey, and B.F. Schmitz. 1991 Annual report of the American Association of Poison Control Centers National Data Collection System. Amer. J. Emerg. Med. 9(1992):461–509. Litovitz, T.L., W. Klein-Schartz, E.M. Caravati, J. Youniss, B. Crouch , S. Lee. 1998 Annual report of the American Association of Poison Control Centers National Data Collection System. Amer. J. Emerg. Med. 17(1999):435–487. Litovitz, T.L., W. Klein-Schartz, S. White, D.J. Cobaugh, J. Youniss, A. Drab, and B.E. Benson. 1999 Annual report of the American Association of Poison Control Centers National Data Collection System. Amer. J. Emerg. Med. 18(2000):517–574. Morton, J.F. Plants poisonous to people in Florida and other warm areas, 2nd ed. Stuart, FL: Southeastern Printing Co., 1982. Muenscher, W.C. Poisonous plants of the United States. New York: Macmillan Co., 1990. Mulligan, G.A. and D.B. Munro. Poisonous plants of Canada. Agri. Canada, Publ. 1842E. Ottawa: Canadian Government Publishing Centre, 1990. Pammel, L.H. A manual of poisonous plants. Cedar Rapids, IA: The Torch Press, 1911. Schmutz, E.M. and L.B. Hamilton. Plants that poison. Flagstaff, AZ: Northland Publishing, Flagstaff, 1979. Sperry, O.E., J. W. Dollahite, J. Morrow, and G.O. Hoffman. Texas range plants poisonous to livestock. Texas Agric. Exp. Sta. Bull. No. 796(1955). Spoerke, D.G., Jr. and S.C. Smolinske. Toxicity of houseplants. Boca Raton, FL: CRC Press, 1990. Stephens, H.A. Poisonous plants of the central United States. Lawrence: Univ. Press of Kansas, 1980. Tampion, J. Dangerous plants. New York: Universe Books, 1977. Tull, D. Edible and Useful Plants of Texas and the Southwest. Austin: Univ. of Texas Press, 1987. Turner, N.W. and A.F. Szczawinski. Common poisonous plants and mushrooms of North America. Portland, OR: Timber Press, 1991. Westbrooks, R.G. and J.W. Preacher. 1986. Poisonous plants of eastern North America. Columbia: Univ. of South Carolina Press, 1986. Barney Lipscomb Leonhardt Chair of Texas Botany Botanical Research Institute of Texas 509 Pecan Street Fort Worth, Texas 76102-4060, USA Table 1. Commonly cultivated and horticultural plants reported to be poisonous (compiled from various sources). Common name Scientific name Toxic part Aconite; Monkshood; Wolfbane Aconitum all parts Alstroemeria Alstroemeria spp. leaves, stems (dermatitis) Angel Trumpet Brugmansia spp. all parts Apple Malus spp. seeds in quantity Azalea; Rhododendron Rhododendron spp. all parts Belladona Atropa belladonna all parts Bittersweet, Climbing or American Celastrus scandens fruits Bittersweet; Nightshade Solanum dulcamara stems, leaves, berries Bleeding Heart Dicentra spp. all parts Bluebonnets Lupinus spp. all parts Bracken Fern Pteridium aquilinum all parts Calla Lily Calla spp. all parts Carnation Dianthus caryophyllus all parts Carolina jessamine, Yellow Gelsemium sempervirens all parts Castor Bean Ricinus communis foliage, seeds China Berry Melia azedarach berries Cladium Cladium spp. leaves, roots Corn poppy; Red Poppy; Field Poppy Papaver rhoeas all parts Crocus, Autumn; Meadow Saffron Colchicum autumnale all parts Cyclamen Cyclamen spp. roots Delphinium; Larkspur Delphinium spp. all parts, esp. seeds Dumbcane Dieffenbachia spp. all parts Elephant Ear Philodendron spp. all parts Flame Lily Gloriosa superba all parts Four-O’Clock Mirabilis spp. roots, seeds Foxglove; Digitalis Digitalis purpurea all parts Golden Chain Tree Laburnum anagyroides fruits Hellebore, White Veratrum album all parts Hellebore; Christmas Rose Helleborus niger all parts Henbane, Black Hyoscyamus niger all parts Holly, English Ilex aquifolium berries Hyacinth Hyacinthus spp. all parts, esp. bulbs Iris Iris spp. underground stems, leaves Ivy, English Hedera helix leaves, berries Jerusalem Cherry Solanum pseudocapsicum leaves, berries Jimsonweed, thorn-Apple, Datura Datura stramonium and spp. all parts Lantana Lantana camara young berries Laurel Cherry Spp. Prunus caroliniana all parts Leather Flower; Virgins Bower Clematis spp. all parts Lily-of-the-Valley Convallaria majalis all parts, esp. rhizomes Mayapple Podophyllum peltatum all parts Mezereon Daphne mezereum all parts Mistletoe Viscum spp., Phoradendron spp. stems, leaves, esp. berries Morning Glory Ipomoea spp. stems, leaves, esp. seeds Mother-in-Law Tongue Sansevieria leaves Narcissus; Daffodil; Jonquil Narcissus spp. all parts, esp. bulbs Oleander; Rosebay Nerium oleander all parts Peach Prunus persica leaves, twigs, seeds Periwinkle Catharanthus roseus all parts Philodendron Philodendron spp. all parts Pieris Pieris japonica leaves Poppy, Opium Papaver somniferum all parts, esp. fruits Potato Solanum tuberosum green stems, leaves Primrose; European Cowslip Primula veris stems, leaves Privet Ligustrum vulgare all parts Rhubarb Rheum rhaponticum leaves Rosary-Pea; Precatory-Bean Abrus precatorius seeds Spathiphyllum; Spath Flower Spathiphyllum spp. all parts Spindle-Tree, European Euonymus europaeus bark, leaves, fruits, seeds St. John’s Wort Hypericum spp. esp. leaves Star-of-Bethlehem Ornithogalum umbellatum all parts, esp. bulbs Sweet Pea Lathyrus odoratus foliage, seeds in quantity Tomato Lycopersicon spp. green parts Tomato Lycopersicon esculentum stems, leaves, vines Tung-Oil Alurites spp. all parts Violet/Pansy Viola spp. seeds Wisteria Wisteria spp. all parts, esp. seeds Yew Taxus spp. all parts Return to 2001 Oktober Gartenfest Table of Contents