Dune onion weed (Trachyandra divaricata) is an upright tufted perennial that is native to South Africa. It has flat, shiny, hairless leaf blades, and a branched flowering stem which produces white and brown striped flowers. The flower stems are able to detach and get swept up in the wind to disperse the seeds as they blow away similar to tumbleweeds. They are commonly found in sandy dunes and coastal areas.
Toxic components T. divaricata is known to be the cause of several poisoning cases in horses and other livestock in South Africa and Australia. Poisoning cases have occurred in situations where horses have had little else to eat. Although the exact toxin is unknown, ingestion of T. divaricata can result in an accumulation of fat-soluble pigment in the horse's nerve tissues, leading to dysfunction of the nervous system.
