Poisonous Plants

1. Poisonous Plants Dr. Jennifer Frick-Ruppert ACEE Executive Director Associate Professor of Ecology and Environmental Studies

2. Poisonous and Medicinal • Just a matter of degree! • Nicotine is a great example: • Cigarettes are smoked because the nicotine is a stimulant; it is also addictive • Nicotine is extremely toxic; on par with cyanide, heroin, atropine. • LD50 is less than 5 mg per kg of body weight. Average lethal dose is 7 drops of pure nicotine. • Nicotine content of cigarettes is regulated to a maximum of 1 mg per cigarette. • Average human is 155 lbs or 70 kg; therefore the LD50 for a 70 kg human is about 350 mg or 350 cigarettes.

3. Some Types of Plant Poisons • Alkaloids • Derived from amino acids; basic (alkali) • Most affect the nervous system because they mimic or block the action of nerve transmitters • Glycosides • Sugar-based with attached subgroup; it is the subgroup that determines toxicity • Cyanogenic glycosides release cyanide; Glucosinolates occur in mustard family; Cardiac glycosides act on heart • Oxalic acid • Crystalline structure is irritating; like glass shards • Rhubarb (Rheum rhabarbarum), Beets (Beta vulgaris), Sorrels (Oxalis spp., Rumex spp.), Purslane (Portulaca oleracea); also Arum family • Phenols • Acidic compounds • Toxicodendron/Rhus species: Poison Ivy, Oak, and Sumac

4. Edible plants and toxins • Potato! • Solanum tuberosum; Nightshade Family • Solanine, a bitter alkaloid • Present in green parts of leaves, sprouts and tubers; ancestral forms even dark tubers • Don’t eat green potatoes! • Taro, Elephant’s Ears • Colocasia esculenta; Arum Family • Staple food of the Pacific Islands • Contain oxalic acid crystals • Prepared by washing and pounding to make poi

5. Passage through Food Chain • Milk sickness • Cattle eat White Snakeroot (Eupatorium rugosum) • Milk from these cows sicken people • Common disease in eastern states; Lincoln’s mother, my neighbors! • Several compounds including glycosides and a complex alcohol (tremetol) • Turtles and poisonous mushrooms • Turtles unaffected; humans that eat the turtles can be sickened

6. Fungal Pathogens on Food • Ergot poisoning • Fungus (Claviceps spp.) growing on Rye or Wheat or other grasses; humans eat the flour • Ascomycete fungus; makes a hard black elongated structure • Grain containing more than 0.3% ergot is prohibited from sale • Over 40 alkaloids present; related to lysergic acid • Symptoms include irritable digestive tract, loss of balance, convulsions, drowsiness • Witch-hunts of Salem and other towns • Aflatoxins/Mycotoxins • Contaminants of grain or other foods • Penicillium, Aspergillus, Monascus commonly • Confusion between plant toxicity and mold toxicity

7. Foxglove • Digitalis purpurea; Figwort Family • Native to England and Europe; naturalized in USA; planted in gardens • Contains a cardiac glycoside • Used to treat “dropsy:” massive fluid retention caused by poor heart function • Now used in controlled dosages to correct heart beat irregularities, improve circulation, relieve fluid buildup, help kidney function

8. Mayapple • Podophyllum peltatum; Barberry Family • Natives used as emetic and worm expellent; also for syphilis • Strongly irritating to skin and poisonous • Contains lignans with anti-cancer and anti-viral properties • Used today to treat venereal warts and testicular cancer

9. Buckeye • Aesculus spp.; Horse Chestnut Family • Main toxin is a saponin glycoside (aesculin) • All parts of plant toxic • Natives used ground leaves to kill fish

10. Cherries, Peaches, Plums, • Prunus spp. Rose Family • Leaves, bark, and seeds (but not fruits) are toxic • Contain a cyanogenic glycoside (amygdalin) resulting in cyanide poisoning if ingested • Almonds are the seeds of a species of Prunus that produces low levels of toxin

11. Poison Ivy, Oak, Sumac • Toxicodendron or Rhus spp. Cashew Family • Variable growth form; climbing or bushy • Leaflets in 3 on compound leaves; alternate leaves • Contains an oleoresin (urushiol) in sap; pollen or smoke also irritating • Poison Sumac has alternate, pinnately compound leaves • Don’t confuse with Virginia Creeper • 5-parted leaves

12. Dolls-Eyes or Baneberry • Actaea pachypoda and A. rubra; Buttercup Family • All parts toxic, especially berries and roots • Undetermined toxin, probably a glycoside • Used by natives as emetic

13. Bloodroot • Sanguinaria canadensis; Poppy Family • Contains several alkaloids including sanguinarine; very toxic • Used to induce glaucoma in laboratory animals

14. False Hellebore • Veratrum parviflorum and others; Lily Family • Contain several alkaloids including veratridine • Can be mistaken for other plants, including edible Ramps • Used to treat high blood pressure

15. Poison Hemlock • Conium maculatum and Cicuta spp.; Umbel Family • NOT the Hemlock tree (Tsuga canadensis) • Resembles wild carrot, but has smooth leaves • Used to poison Socrates • European weed, now naturalized USA • Contains toxic alkaloids related to nicotine

16. Pokeweed • Phytolacca americana; Pokeweed Family • Several toxic compounds, mostly saponins, but recently a mitogen that damages blood cells • Young stalks commonly eaten after boiling in several waters • No longer recommended

17. References • NJ Turner and AF Szczawinski. 1991. Common Poisonous Plants and Mushrooms of North America. Timber Press, Oregon. • S Foster and JA Duke. 1990. Peterson Field Guides Eastern/Central Medicinal Plants.Houghton Mifflin Company, Boston. • A Krochmal and C Krochmal. 1984. A Field Guide to Medicinal Plants. Random House, NY. • Most of the photos in this presentation were from these references or from various internet sites. Do not distribute them.