Prickly comfrey
General poisoning notes:
Prickly comfrey (Symphytum asperum) is a naturalized herb found in parts of southern Canada. The plant contains pyrrolizidine alkaloids, which can cause veno-occlusive symptoms leading to liver cirrhosis. The plant can also accumulate toxic amounts of nitrates. Animals do not normally eat the plant because of the bristly hairs on the leaves. However, swine given the plant as green fodder showed signs of nitrate poisoning. Long-term use of the plant as food could lead to liver dysfunction (Cooper and Huxtable 1984, Huxtable 1989).
Nomenclature:
Scientific Name: Symphytum asperum Lepech.
Vernacular name(s): prickly comfrey
Scientific family name: Boraginaceae
Vernacular family name: borage
Symphytum asperum Lepech.
Geographic Information
British Columbia, Manitoba, Nova Scotia, Ontario, Prince Edward Island, Quebec.
Toxic parts:
All parts, leaves, roots, stems.
Notes on Toxic plant chemicals:
This plant contains pyrrolizidine alkaloids such as echimidine. These alkaloids cause veno-occlusive symptoms in animals. Total alkaloid content (as a percentage of dry weight) for fresh leaves is about 0.01% and for dry leaves, about 0.059%. Many members of the genus contain much higher concentrations of alkaloids in the roots (Huxtable 1989).
Toxic plant chemicals:
Echimidine, nitrate.
Echimidine
Animals/Human Poisoning:
Note: When an animal is listed without additional information, the literature (as of 1993) contained no detailed explanation.
Swine
General symptoms of poisoning:
Breathing, labored, cyanosis, methemoglobinemia.
Notes on poisoning:
Prickly comfrey is not normally ingested by animals because of the bristly hairs on the leaves. This plant can accumulate nitrates. In Britain, swine were poisoned when given prickly comfrey as green fodder. Symptoms were typical for nitrate poisoning, including apathy, labored breathing, cyanosis, and methemoglobinemia (Cooper and Johnson 1984).
