Sheep-laurel (Common name)

General poisoning notes:

Sheep-laurel (Kalmia angustifolia) is a native shrub found in eastern Canada in boggy areas. This plant contains a toxin that has poisoned cattle, goats, and sheep as well as humans. Poisoning rarely happens in the wild. Other animals have been poisoned by sheep-laurel, including zebras at a zoo, as well as horses. Meat of chickens that had ingested sheep-laurel may be toxic to other animals. The nectar contains the toxin that results in toxic honey (Marsh 1930, Kingsbury 1964, Verlangieri 1976, Lampe and McCann 1985).

References:

  • Kingsbury, J. M. 1964. Poisonous plants of the United States and Canada. Prentice-Hall Inc., Englewood Cliffs, N.J., USA. 626 pp.
  • Lampe, K. F., McCann, M. A. 1985. AMA Handbook of poisonous and injurious plants. American Medical Assoc. Chicago, Ill., USA. 432 pp.
  • Marsh, C. D. 1930. Mountain-laurel (Kalmia latifolia) and sheep laurel (Kalmia angustifolia) as stock-poisoning plants. U. S. Dept. Agric. Tech. Bull., 219. 22 pp.
  • Pritchard, W. R. 1956. Laurel (Kalmia angustifolia) poisoning of sheep. N. Am. Vet., 37: 461-462.
  • Verlangieri, A. J., Gawlikowski, J. N., Shapiro, R. 1976. Acute toxicity of Kalmia angustifolia, (sheep laurel) extracts in the rat. Vet. Toxicol., 18: 122-124.

Nomenclature:

Scientific Name:
Kalmia angustifolia L.
Vernacular name(s):
sheep-laurel
Scientific family name:
Ericaceae
Vernacular family name:
heath

Go to ITIS*ca for more taxonomic information on: Kalmia angustifolia

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

Plant or plant parts used in or around the home.

  • 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: sheep-laurel - Google Search

Notes on Poisonous plant parts:

The entire plant is poisonous, including the nectar and honey made from it (Pritchard 1956, Kingsbury 1964).

Toxic parts:

  • all parts
  • flowers
  • leaves
  • mature fruit
  • stems

References:

  • Pritchard, W. R. 1956. Laurel (Kalmia angustifolia) poisoning of sheep. N. Am. Vet., 37: 461-462.
  • Verlangieri, A. J., Gawlikowski, J. N., Shapiro, R. 1976. Acute toxicity of Kalmia angustifolia, (sheep laurel) extracts in the rat. Vet. Toxicol., 18: 122-124.

Notes on Toxic plant chemicals:

Andromedotoxin and resins derived from diterpenes are the toxic compounds found in all the toxic species of the heath plant family. The toxin is found even in the nectar of flowers (Fuller and McClintock 1986). Experimental poisoning of rats using leaf extracts resulted in an average LD-50 (female) of 8.2 g of green leaves per kilogram body weight. The leaves were toxic only in the spring. Leaves of plants growing in wet areas were more toxic than those growing in dry areas (Verlangieri et al. 1976).

Toxic plant chemicals:

  • andromedotoxins

References:

  • Verlangieri, A. J., Gawlikowski, J. N., Shapiro, R. 1976. Acute toxicity of Kalmia angustifolia, (sheep laurel) extracts in the rat. Vet. Toxicol., 18: 122-124.

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:

Notes on poisoning:

Experimental poisoning of cattle showed symptoms, including soft feces, salivation, vomiting, diarrhea, and incoordination. Consuming green leaves equivalent to 0.2% of an animal''s body weight was determined to cause toxic signs in cattle (Marsh 1930). A few cattle in the field were poisoned after ingesting sheep-laurel (Kingsbury 1964).

References:

  • Kingsbury, J. M. 1964. Poisonous plants of the United States and Canada. Prentice-Hall Inc., Englewood Cliffs, N.J., USA. 626 pp.
  • Marsh, C. D. 1930. Mountain-laurel (Kalmia latifolia) and sheep laurel (Kalmia angustifolia) as stock-poisoning plants. U. S. Dept. Agric. Tech. Bull., 219. 22 pp.

Goats

General symptoms of poisoning:

Notes on poisoning:

Experimental poisoning of goats fed green leaves resulted in symptoms, including profuse vomiting, staggering, recumbency, weakness, shallow breath, and teeth grinding. Sheep-laurel causes toxic signs in goats if ingested green material equaled at least 0.25% of animal body weight (Marsh 1930).

References:

  • Kingsbury, J. M. 1964. Poisonous plants of the United States and Canada. Prentice-Hall Inc., Englewood Cliffs, N.J., USA. 626 pp.

Humans

General symptoms of poisoning:

References:

  • Lampe, K. F., McCann, M. A. 1985. AMA Handbook of poisonous and injurious plants. American Medical Assoc. Chicago, Ill., USA. 432 pp.

Rodents

General symptoms of poisoning:

References:

  • Verlangieri, A. J., Gawlikowski, J. N., Shapiro, R. 1976. Acute toxicity of Kalmia angustifolia, (sheep laurel) extracts in the rat. Vet. Toxicol., 18: 122-124.

Sheep

General symptoms of poisoning:

Notes on poisoning:

Experimental poisoning of a goat caused symptoms of poisoning similar to those seen in sheep. A dosage of green leaves equal to 0.5% of an animal''s body weight caused symptoms to occur (Clawson 1933).

References:

  • Kingsbury, J. M. 1964. Poisonous plants of the United States and Canada. Prentice-Hall Inc., Englewood Cliffs, N.J., USA. 626 pp.
  • Pritchard, W. R. 1956. Laurel (Kalmia angustifolia) poisoning of sheep. N. Am. Vet., 37: 461-462.

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