Astragalus (Astragalus membranaceus) is a Chinese herbal remedy that comes from the root of a plant in the pea family. This plant is a relative of our locoweed, which is toxic to livestock. The Chinese species is nontoxic, the source of a very popular medicine called huang qi that you can buy in any drugstore in China for use against colds, flus, and other respiratory infections. Recent studies in the West confirm its antiviral and immune-boosting effects.