Canada nettle-Laportea canadensis (L.) Gaud.-Poisonous plant

Canada nettle

General poisoning notes:

Canada nettle (Laportea canadensis) is found in moist woods and along streams. This plant has stinging hairs on the leaves and stem that readily penetrate thin-skinned areas on humans. The tips of the hairs break off, allowing the contained liquid to penetrate the body. Intense localized itching results. Applying water to the surface of the affected area can increase the sensation; this problem may persist for several weeks. In Australia, other members of the genus Laportea have caused severe reactions in humans, and a death was reported in New Guinea after severe exposure. Livestock have responded frantically to contact with these plants in Australia. Canada nettle can cause reactions in animals upon exposure in Canada. Avoid this plant if possible (MacFarlane 1963, Mitchell and Rook 1979).

Nomenclature:

Scientific Name: Laportea canadensis (L.) Gaud.

Vernacular name(s): Canada nettle

Scientific family name: Urticaceae

Vernacular family name: nettle

Geographic Information

Manitoba, New Brunswick, Nova Scotia, Ontario, Quebec, Saskatchewan.

Notes on Poisonous plant parts:

Canada nettle is covered with stinging hairs on the leaves and stem. The tips of the hairs are readily fractured on contact with skin, allowing the internal liquid to be injected into the local body area. The hairs are sharply pointed, allowing ready penetration of thinner skinned portions of the body (MacFarlane 1963).

Toxic parts:

Hairs

Notes on Toxic plant chemicals:

The active ingredient in the stinging hairs is not known. The chemicals acetylcholine, histamine, and 5-hydroxytryptamine, which cause the stinging of hairs from the closely related American stinging nettle (Urtica dioica), are not the primary toxic chemicals in Canada nettle. Some studies on native Australian Laportea species have shown that no detectable loss of activity occurs after 46 years in a dry state. Immersion in boiling water for 10 min does not deactivate the chemical. In fact, the pain is intensified in humans if the affected area is exposed to water, a reaction that may last for many weeks (MacFarlane 1963).

Toxic plant chemicals:

unknown chemical

Animals/Human Poisoning:

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

Humans

General symptoms of poisoning:

Erythema, itchiness, pain, skin, flushed.

Notes on poisoning:

Canada nettle hairs induce localized pain and discomfort as well as erythema, reddening, and localized sweating. The pain may persist for weeks. Canada nettle differs from American stinging nettle (Urtica dioica) in that the intense pain can persist for weeks or months (MacFarlane 1963, Mitchell and Rook 1979).