Onoclea sensibilis (Scientific name)

General poisoning notes:

Sensitive fern (Onoclea sensibilis) is a native plant that is found through eastern Canada into Manitoba. The plant, often abundant in low, wet areas, has been implicated in the poisoning and death of horses in field cases. Only one set of experimental poisonings has been undertaken, but the resulting symptoms were similar when horses were fed hay containing sensitive fern (Waller et al. 1944).

References:

  • Waller, E. F., Prince, F. S., Hodgon, A. R., Colovos, N. F. 1944. Sensitive-fern poisoning of horses. Univ. N. H. Agric. Stn. Tech. Bull., 83. 7 pp.

Nomenclature:

Scientific Name:
Onoclea sensibilis L.
Vernacular name(s):
sensitive fern
Scientific family name:
Polypodiaceae
Vernacular family name:
frern

Go to ITIS*ca for more taxonomic information on: Onoclea sensibilis

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

  • Labrador
  • Manitoba
  • New Brunswick
  • 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: Onoclea sensibilis - Google Search

Notes on Poisonous plant parts:

When the fronds (aboveground leaves) are included in hay, they produce toxic symptoms in horses. The fertile fronds (spore-bearing stalks) are also included in hay. A literature search did not reveal any reports on the toxin, nor was the plant organ that contains the toxin identified.

Toxic parts:

  • leaves

References:

  • Waller, E. F., Prince, F. S., Hodgon, A. R., Colovos, N. F. 1944. Sensitive-fern poisoning of horses. Univ. N. H. Agric. Stn. Tech. Bull., 83. 7 pp.

Toxic plant chemicals:

  • unknown chemical

References:

  • Waller, E. F., Prince, F. S., Hodgon, A. R., Colovos, N. F. 1944. Sensitive-fern poisoning of horses. Univ. N. H. Agric. Stn. Tech. Bull., 83. 7 pp.

Animals/Human Poisoning:

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

Horses

General symptoms of poisoning:

Notes on poisoning:

Ingesting hay containing sensitive fern produces the following symptoms: difficulty in eating, falling down, walking as if blind, rubbing against objects, and death. Postmortem examination showed extreme icterus, swollen liver, paralysis of the alimentary tract, and brain edema. Old horses are more affected than younger ones. Horses that are worked and are fed a grain supplement, in addition to hay that includes the fern, are not affected. Recovery may occur if the horses are given good hay and grain before serious nervous symptoms develop Waller et al. 1944).

References:

  • Waller, E. F., Prince, F. S., Hodgon, A. R., Colovos, N. F. 1944. Sensitive-fern poisoning of horses. Univ. N. H. Agric. Stn. Tech. Bull., 83. 7 pp.

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