Tarbush, Blackbrush

Flourensia cernua DC.

Asteraceae (Sunflower Family)


Description

Tarbush is a strongly aromatic, perennial shrub of the Sunflower family. Its stems are brittle and have a characteristic black color.

The plant's height may vary from 1 foot tall on dry sites to more than 6 feet tall in deep, overflow areas. It is most common on deep soils. The roots are shallow to take advantage of the quick thunderstorms common to the desert region where it grows.

The leaves of tarbush are smooth along the edges and oval or oblong. They are located alternately along the stems. The flowers are solitary in the leaf axils (the angle between the upper leaf and the leaf stem), forming a leafy flowering stem in the fall.

The forage value of tarbush is poor for livestock and wildlife.


Habitat

Tarbush is common on dry plains, hills and mesas from counties just east of the Pecos River in Texas, west to Arizona and south to Mexico.


Toxic Agent

Tarbush may poison sheep, goats and cattle. The toxin in tarbush is unknown. In experiments, sheep and goats were force-fed tarbush fruits, which were lethal at about 1 percent of the animal's weight. Individual susceptibility varied considerably, and the difference between toxic and lethal doses was small. In moderate amounts, the foliage was not toxic.


Signs of Livestock Ingestion

On the range, clinical signs appear a day or less after an animal eats a toxic amount of the plant. Depending on the amount ingested, death may follow within 24 to 72 hours, or occasionally longer. Some animals recover rapidly after showing clinical signs for several days to a week. Signs are modified somewhat by the severity of poisoning, but generally consist of: Loss of appetite; Abdominal pain; Reluctance to move; Occasional respiratory distress.

Acute cases may salivate profusely. Animals generally remain on their feet until shortly before dying without struggle. Poisonings occur mostly in January through March after the fruit has matured but before it falls.


Images