It is a noxious weed becoming invasive in waste areas.
Widely throughout North America
Hoary Alyssum (Berteroa inana)
The specific toxin in hoary alyssum has not been determined. Both the green and dried plant is toxic. Hay contaminated with the plant is often the source of the problem.
An erect branching annual growing 2-3 feet in height. It has alternate, narrow, lanceolate leaves that are densely covered with white hairs that give the leaves and stems a gray-green appearance. The flowers are produced at the ends of the branches, and are white with 4 deeply divided petals. The seed pods are basically round and slightly falttened containing 6 brown seeds.
Diarrhea can develop in severely poisoned horses that can cause dehydration, secondary hypovolemic shock and death if untreated.
Horses develop lameness after eating hoary alyssum due to swelling of the legs and laminitis. Signs range from stiffness, swollen lower legs, laminitis and severe lameness.
Affected horses should be taken off of the hay or pasture that contains the hoary alyssum and treated with oral and intravenous fluids if diarrhea nad shock have developed. Recovery is usually uneventful if the horse is treated early in the course of poisoning.
Pregnant mares may abort if they consume significant quantities of hoary alyssum.
Hoary alyssum should be mowed or treated with herbicides before it flowers and forms seeds. Left to its own, Hoary alyssum is an invasive weed.