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POTATO - Solanum tuberosum

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Distinguishing features

A 0.4-1 meter tall perennial herb with an erect, branched stem and underground stolons bearing tubers. Flowers resemble those of the tomato, but are white in color. 

This is a large genus of plants with over ~ 1500 species distributed worldwide.  Various species are found throughout the U.S.  The ones of particular concern in the U.S. include Solanum nigrum (black nightshade), S. dulcamara (bittersweet nightshade), S. tuberosum (potato) and S. carolinense (horsenettle).
Toxic Principle:  there are several glycoalkaloids (alkaloids + sugars) that are potentially toxic.  A prototypical glycoalkaloid is called solanine (sugar [solanose] + alkaloid [solanidine] = solanine).  The akaloidal portion of the glycoalkaloid is also generically referred to as an aglycone.  The intact glycoalkaloid is poorly absorbed from the GI tract but causes GI irritation.  The aglycone is absorbed and is believed to be responsible for observed nervous system signs.
Toxicity:  toxicity of a given species can vary widely due to environmental conditions, part of the plant or degree of maturity.  Unripe berries are more toxic than ripe berries.  Berries are more toxic than leaves which, in turn, are more toxic than stems or roots.  Overall plant glycoalkaloid content is often higher in the autumn than in the spring. 


Clinical signs: the symptoms observed in a given case will depend on the balance of the irritant effect of the intact glycoalkaloid vs. the nervous system signs caused by the aglycone.  GI signs include anorexia, nausea, salivation, abdominal pain, emesis, constipation or diarrhea (with or without blood).  Nervous system signs include apathy, drowsiness, progressive weakness/paralysis, prostration and unconsciousness.  Nervous signs build to a maximum followed by death or recovery within 1 to 2 days. 

Laboratory diagnosis: although not routinely available, detection of alkaloids in tissues or urine is possible.

Lesions:  gastroenteritis, detection of plant fragments in GI tract.





Tox Factoid: ordinary potatoes, if grown too close to the soil surface, will develop a green skin due to sun exposure.  The green skin (in addition to young sprouts) can contain harmful glycoalkaloids. Green tissue should be removed from potatoes before eating.


Copyright 2002

University of Pennsylvania
Created by:    Alexander Chan (2003), Daphne Downs (2002), Chris Tsai (2001), Brett Begley (2000), Janet Triplett (1997)
Faculty Advisor:  Dr. Robert Poppenga