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Viscum
Viscum album L. Family: Loranthaceae (Viscaceae) Common Names: European
Mistletoe, Mistletoe Description: This parasite grows primarily on the trunks of deciduous trees, particularly the apple. Stems are much branched, and the leaves are 2 to 3 inches long, thick, leathery, and usually a pale yellowish-green. The fruit is a sticky white berry. Distribution: This European plant was introduced into Sonoma County, California. Toxic Part: Only the leaves
and stems are toxic. The berries have very low toxin concentration and cause toxicity only if ingested in large quantities. Toxin: Viscumin, a plant Viscum album, branch with immature fruit
lectin (toxalbumin) related to ricin.
Clinical Findings: The toxin is similar in action to the lectins contained in Abrus
precatorius and Ricinus communis but is less potent. Following a latent period of many hours, nausea, vomiting, abdominal cramping, diarrhea, and dehydration occur. Management: Patients with symptoms need to be assessed for signs of dehydration and electrolyte abnormalities. Activated charcoal should be administered. Intravenous hydration, antiemetics, and electrolyte replacement may be necessary in severe cases, particularly those involving children. Consultation with a Poison Control Center should be considered. See “Poisoning by Plants with Toxalbumins,” p. 33. References Franz H. Mistletoe lectins and their A and B chains. Oncology 1986;43(suppl 1): 23–34.