Mountain Mahogany

Cercocarpus montanus

Rosaceae

Description

Three varieties of mountain mahogany grow in Texas. Members of the rose family, they are identified most easily by the fuzzy, twisted awn attached to each fruit. The leaves are simple and often more than 1 inch long with heavily toothed margins. This is an excellent browse plant for deer and elk.

Habitat

Mountain mahogany grows primarily on ledges and rims of rough terrain in western Texas. Varieties can be found in the Trans-Pecos, Edwards Plateau and Plains regions in Texas. It also grows from Kansas to Arizona, South Dakota and Montana.

Toxic Agent

Mountain mahogany contains concentrations of cyanogenic glycosides that under certain conditions are broken down to release cyanide. The toxins in the plant are usually, but not always, below the dangerous level. Influences such as bruising, wilting, withering or drying of leaves appear to contribute to cyanide production. Wilted leaves from cutting the plant appear to be the most dangerous. All domestic animals are subject to cyanide poisoning, although ruminants are the most susceptible.

Signs of Livestock Ingestion

Cyanide is one of the most rapidly acting poisons. Signs of illness may start within 5 minutes from the time the animal begins eating the plant. Death may occur within 15 minutes or several hours. Clinical signs generally occur in this order: Salivation and labored breathing; Muscle tremors; Incoordination; Bright red venous blood; Convulsions; Death from respiratory failure.

Management Strategies

Even plants containing a high level of cyanogenic glycoside may not poison livestock. Because poisoning depends on the presence of free cyanide, anything preventing its development in the gastrointestinal tract can lessen or eliminate the danger of poisoning. Certain feeds, such as alfalfa hay and linseed cake, retard the production of cyanide and may prevent poisoning.

If signs are typical of cyanide poisoning, treat with sodium nitrite followed by sodium thiosulfate. Remove animals from infested pastures at the first signs of poisoning.