Yellow starthistle (Centaurea solstitialis) - Cows have eaten this weed in pasture in California
        Yellow starthistle is annual that grows 2 to 3 feet tall. The weed probably arrived as a contaminant in alfalfa seed in the mid-1800s to early 1900s. They are "allelopathic" meaning they produce chemicals in the soil which reduce the ability of other plants to grow in their vicinity. For additional information visit this UC Davis sponsored website about Yellow star thistle.
        Nutrients: Based on what we know about how animals choose what to eat and the fact that cattle have successfully eaten it in research projects it is fair to assume that this plant will have good nutritional value.
        Toxins: There are no known cases of poisoning of cattle eating yellow star thistle. In fact, cows goats and sheep have been successfully used to control the plant in research done at UC Davis. However, Yellow star thistle does contain an unidentified compound that causes chewing disease in horses. The compound damages the area of their brains that controls fine motor movements, including mouth and lip movements. According to Burrows and Tyrl "There seems to be cumulative storage of the toxins rather than cumulative effect or damage. Thus amounts of the plant that migh otherwise produce disease - .... 100% of body weight - may be eaten without deleterious efect if not consumed on a continuous basis."