There are many common roadside, household, and garden plants that are poisonous, if ingested in whole or in part. Many may be fatal. So it's a good idea, especially if small children are around, to identify the potential problems in or near your yard and living space. The scope of this article is to help you identify some of these plants, their toxic part(s), and some of the poisoning symptoms. For a more comprehensive listing and in-depth explanation, there is a good reference in the UofA Sierr Vista Cooperative Extension office: Plants That Poison the reference for this article, by Ervin M. Schmutz, Ph.D. and Lucretia Breazeale Hamilton. Dr. Schmutz has also authored Livestock Poisoning Plants of Arizona.  Both books are out of print but are available through the Cochise County Library System.

Apples: seeds; eaten in quantity result in cyanide poisoning.

Asparagus: berries may poison humans; young plants may cause dermatitis.

Bird-of-Paradise Bush: pods and seeds; diarrhea, nausea, vomiting.

Broad Bean (fava bean): seeds or pollen; in people of Greek, Italian, or Black descent, may cause severe, possibly fatal, hemolytic anemia in those with inherited deficiency in glucose-6-phosphate dehydrogenase (an essential enzyme).

Buttercups: entire plant; most toxic when flowering; digestive upset, skin ulcerations; may be fatal.

Caladium: all parts; burning of tissue; severe swelling; may cause fatality if breathing impaired.

Candelabra-Cactus (Euphorbia lacteal): leaves, stems, and sap; highly toxic; temporary blindness, diarrhea, vomiting, stomach pain, irritation of mouth parts, throat, and skin.

Carolina Jessamine (Gelsmium sempervirens): entire plant; sweating, convulsions, paralysis, muscular weakness, double vision.

Cestrums (jessamines): berries and leaves; salivation, fever, dilation of pupils, paralysis, Cestrum nocturnum, a neighboring variety can cause headaches, dizziness, and nausea.

Dumbcanes (Dieffenbachia sp.): entire plant; choking, nausea, salivation. Eggplant: leaves, stems, and fruit are possibly poisonous; no documented symptoms; eat only cooked, ripe, healthy fruit.

Elderberries: roots, leaves, bark, stems, unripe berries; nausea, vomiting, and diarrhea; ripe fruit is harmless. Hopbush: leaves and bark; contains saponins; used as a fish poison, no reported symptoms.

Mescal Bean: entire plant; nausea, vomiting, hallucinations, coma, death.

Mexican Gold Poppy: juice of fruit; a narcotic.

Mistletoe: all parts, especially berries; digestive upset, slow pulse, collapse, death. Mushrooms (Amanitas): entire plant; some cause death or permanent organ damage; wild mushroom identification requires expert knowledge.

Oleander: entire plant and honey made from; nausea, vomiting, dizziness, irregular heartbeat, convulsions, coma, death.

Onions: bulbs; large amounts ingested in a short time may cause death; general use in human diet is o.k.

Peas: entire plant, especially seeds; when eaten in large amounts, possible skeletal deformities, tremors, weakness, and convulsions.

Peach: seeds; cyanide poisoning.

Philodendron: entire plant; nausea, swelling of mouth and throat, cats have been fatally poisoned by them.

Poinsettia: stems, leaves, sap; gastric distress.

Potato: sprouts, unripe berries, green or spoiled fruit; digestive upset, dilated pupils, shock, paralysis, and death.

Pyracantha: berries suspect; symptoms unknown; jelly from is ok.

Spinach: leaves contain salts of oxalic acid; large, regular amounts and low calcium diet can result in calcium deficiency.

Sacred Datura: all parts; thirst, red skin, nausea, vomiting, headache, delirium, coma.

Tomato: all parts but fruit; digestive upset.  An online search yields some conflicting results. Some claim tomato leaves are edible in small quantities for humans.  All state that the tomato plant is poisonous to dogs and other smaller animals.  

Violet (pansy): seeds; large quantities could be serious for a child.

BULBS: Belladonna Lily (Amaryllis belladonna): bulbs; contain dangerous, poisonous alkaloids which cause respiratory paralysis. Daffodil, Hyacinth, Jonquil, Narcissus: bulbs; nausea, vomiting, diarrhea; may be fatal. Iris (flags and fleur-de-lis): leaves and rootstock; digestive upset.

and remember, saliva causes cancer, especially when swallowed frequently and in small amounts over a long period of time.