Colorado rubberweed-Hymenoxys richardsonii (Hook.) Cockerell-Poisonous plant

Colorado rubberweed

General poisoning notes:

Colorado rubberweed (Hymenoxys richardsonii) is a native herb found in the southern prairies. This plant has caused poisoning and death in sheep, goats, and occasionally cattle. Sheep and goats consume this plant when there is little else to eat. Poisoning is therefore most frequent in spring and late autumn, when other forage is reduced. Cattle are poisoned less frequently because they find the plant unpalatable (Cheeke and Schull 1985).

Nomenclature:

Scientific Name: Hymenoxys richardsonii (Hook.) Cockerell

Vernacular name(s): Colorado rubberweed

Scientific family name: Compositae

Vernacular family name: composite

Geographic Information

Alberta, Saskatchewan

Toxic parts:

All parts, leaves, stems

Notes on Toxic plant chemicals:

Hymenovin (hymenoxon) is a sesquiterpene lactone that contains an alpha-methylene-gamma-lactone moiety. This moiety inhibits the enzymatic capability of adenylate cyclase by alkylation of its thiol group. The inhibition can disrupt the cellular transmission of external signals to the internal regulatory proteins. Mercaptans, such as cysteine, may be used in treatment by partly detoxifying the moiety before it can damage cellular enzymes (Elissalde and Ivie 1987). The oral LD-50 of hymenovin (hymenoxon) is 2.9-8.5 g/kg in sheep (Cheeke and Schull 1985).

Toxic plant chemicals:

Hymenovin

Animals/Human Poisoning:

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

Cattle

Goats

Sheep

General symptoms of poisoning:

Death, kidney, congestion of, liver, congestion of, lungs, congestion of, vomiting.

Notes on poisoning:

Symptoms of ingestion include violent vomiting, hence the name spewing sickness. Sheep may have a green stain around the mouth. Vomited material can be inhaled, which can lead to inhalation pneumonia, permanent lung damage, or death. Lesions in the gastrointestinal tract, liver and kidney congestion, and lung damage occur. Frequent coughing and sneezing occur (Parker, Cheeke and Schull 1985).