Notes on poisoning: St. John's-wort

General poisoning notes:

St. John''s-wort (Hypericum perforatum) is a naturalized herb found in eastern Canada and British Columbia. The plant contains hypericin, which is a primary photosensitizing chemical. Ingestion has caused skin problems in cattle, horses, rabbits, sheep, and swine. The skin problems occur on white or light-colored skin; dark skin is not affected. Severe symptoms such as convulsions, staggering, and coma have occurred in some animals. Loss of wool quality occurs in sheep, and the meat of affected animals is of poor quality. This plant is widespread in Canada. The reaction is more severe if fresh plants are eaten, but dried plants can also cause photosensitization, even though 80% of the hypericin is lost (Araya and Ford 1981, Cooper and Johnson 1984, Crompton et al. 1988).

References:

Araya, O. S., Ford, E. J. 1981. An investigation of the type of photosensitization caused by the ingestion of St John's wort (Hypericum perforatum) by calves. J. Comp. Pathol., 91: 135-141.

Cooper, M. R., Johnson, A. W. 1984. Poisonous plants in Britain and their effects on animals and man. Her Majesty's Stationery Office, London, England. 305 pp.

Crompton, C. W., Hall, I. V., Jensen, K. I., Hildebrand, P. D. 1988. The biology of Canadian weeds. 83. Hypericum perforatum L. Can. J. Plant Sci., 68: 149-162.

Nomenclature:

Scientific Name: Hypericum perforatum L.

Vernacular name(s): St. John's-wort

Scientific family name: Guttiferae

Vernacular family name: St. John's-wort

Go to ITIS*^ca for more taxonomic information on: Hypericum perforatum

References:

Agriculture Quebec. 1975. Noms des maladies des plantes du Canada/ Names of plant diseases in Canada. , Quebec City, Que., Canada. 288 pp.

Alex, J. F., Cayouette, R., Mulligan, G. A. 1980. Common and botanical names of weeds in Canada/Noms populaire et scientifiques des plantes nuisibles du Canada. Revised. Agric. Can. Publ., Ottawa, Ont., Canada. 132 pp.

Bailey, L. H., Bailey, E. Z. 1976. Hortus third. Revised. MacMillan, New York, N.Y., USA. 1290 pp.

Scoggan, H. J. 1978, 1979. The flora of Canada. Nat. Mus. Nat. Sci. (Ottawa) Publ. Bot. 7(1)-7(4). 1711 pp.

Van Wijk, H. L. 1911. A dictionary of plant names. Martinus Nijhoff, The Hague, The Netherlands. 1444 pp.

Victorin, M. 1964. Flore Laurentienne. 2nd ed. Univ. Montreal, Montreal, Que., Canada. 952 pp.

Geographic Information

British Columbia
New Brunswick
Newfoundland
Nova Scotia
Ontario
Prince Edward Island
Quebec

References:

Bailey, L. H., Bailey, E. Z. 1976. Hortus third. Revised. MacMillan, New York, N.Y., USA. 1290 pp.

Boivin, B. 1966, 1967. Énumération des plantes du Canada. Provencheria 6. Nat. Can. (Que.) 93: 253-274; 371-437; 583-646; 989-1063. 94: 131-157; 471-528; 625-655.

Image or illustration

Images: images.google.com

Toxic parts:

flowers
leaves

References:

Araya, O. S., Ford, E. J. 1981. An investigation of the type of photosensitization caused by the ingestion of St John's wort (Hypericum perforatum) by calves. J. Comp. Pathol., 91: 135-141.

Notes on Toxic plant chemicals:

Hypericin, a fluorescent pigment, is regarded as a derivative of naphthodianthrone. The pigment is contained in small black dots that are just visible to the naked eye on leaves and petals. The chemical is a primary photosensitizer because the photodynamic action occurs in the skin (Araya and Ford 1981).

Toxic plant chemicals:

hypericin

References:

Araya, O. S., Ford, E. J. 1981. An investigation of the type of photosensitization caused by the ingestion of St John's wort (Hypericum perforatum) by calves. J. Comp. Pathol., 91: 135-141.

Animals/Human Poisoning:

Note: When an animal is listed without additional information, the literature (as of 1993) contained no detailed explanation.

Cattle

General symptoms of poisoning:

References:

Araya, O. S., Ford, E. J. 1981. An investigation of the type of photosensitization caused by the ingestion of St John's wort (Hypericum perforatum) by calves. J. Comp. Pathol., 91: 135-141.

Horses

General symptoms of poisoning:

References:

Cooper, M. R., Johnson, A. W. 1984. Poisonous plants in Britain and their effects on animals and man. Her Majesty's Stationery Office, London, England. 305 pp.

Rabbits

General symptoms of poisoning:

References:

Cooper, M. R., Johnson, A. W. 1984. Poisonous plants in Britain and their effects on animals and man. Her Majesty's Stationery Office, London, England. 305 pp.

Sheep

General symptoms of poisoning:

References:

Cooper, M. R., Johnson, A. W. 1984. Poisonous plants in Britain and their effects on animals and man. Her Majesty's Stationery Office, London, England. 305 pp.

Swine

General symptoms of poisoning:

References:

Cooper, M. R., Johnson, A. W. 1984. Poisonous plants in Britain and their effects on animals and man. Her Majesty's Stationery Office, London, England. 305 pp.