The Importance of Poisonous Plants as Forages in the Prairies and Southwest
Grazing animals are generally exposed to a wide variety of potentially poisonous plants. If grazing pressures are not too great, animals usually avoid these plants, consume them in quantities that can be safely detoxified or excreted, or select them as diet constituents when toxins are at a safe level. Silverleaf nightshade is a widely distributed, poisonous, warm-season, perennial weed found throughout the southwestern states. Forage poisoning in grazing animals usually results from three conditions: consumption of plants that are toxic in small amounts; consumption of plants considered good forage when consumed in moderate amounts, but toxic if selected in excess; or consumption of plants usually considered good forage, but consumed at a time when they are toxic. Mescalbean is highly poisonous and contains the narcotic alkaloid cytisine or sophorine. Hogplum is most comonly found in the Cross Timbers, Edwards Plateau, and South Texas Plains regions.