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).
Description
Perennial herb. Stems 10-110 cm long, erect, or sometimes rooting at the base, 2-lined, smooth, with branches ascending. Leaves sessile or subsessile, 5-35 mm long, 2-14 mm broad, narrowly ovate to elliptic-oblong or linear or sometimes oblanceolate, apex obtuse or mucronate to rounded, base cuneate to rounded, entire with intramarginal and often a few laminar black glands. Inflorescence a (1-)5-many-flowered, subcorymbose or broadly pyramidal cyme with ultimately monochasial branches; flowers 1.5-2.5 cm in diameter. Sepals 3-6 mm long, lanceolate to oblong or elliptic, acute to acuminate or shortly aristate, free, entire.. Petals + narrowly oblanceolate, 8-15 mm long, with marginal black dots and sometimes (not in Pakistan) laminar black lines. Stamens in `3' fascicles (2+2+1). Ovary 3-locular, 2-3.5 mm long; styles c. 2 x longer than the ovary, free, divergent, incurved near apex. Capsule (4-)5-9 mm long, ovoid to pyramidal, each valve with dorsal vittae and lateral vescicles, Seeds 1.0-1.2 mm long, shortly apiculate, not carinate; testa reti¬culate-pitted.
Nomenclature:
Scientific Name: Hypericum perforatum L.
Vernacular name(s): St. John's-wort
Scientific family name: Guttiferae
Vernacular family name: St. John's-wort
Hypericum perforatum L.
Geographic Information
Europe and N. Africa to W. China and N.W., India (Kumaun). Introduced into E. Asia, America. Australasia and S. Africa.
Canada: British Columbia, New Brunswick, Newfoundland, Nova Scotia, Ontario, Prince Edward Island, Quebec.
Toxic parts:
Flowers, leaves.
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.
Hypericin
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:
Muzzle, dry, restlessness, skin, dry.
Horses
General symptoms of poisoning:
Appetite, loss of, coma, gait, staggering, skin, peeling of.
Rabbits
General symptoms of poisoning:
Death, liver, cirrhosis of, skin, peeling of.
Sheep
General symptoms of poisoning:
Convulsions, erythema, skin, peeling of.
Swine
General symptoms of poisoning:
Skin, flushed, skin, peeling of.
