trompillo: weedy nightshade with silvery foliage and violet or blue or white flowers; roundish berry widely used to curdle milk; central United States to South America
nightshade: any of numerous shrubs or herbs or vines of the genus Solanum; most are poisonous though many bear edible fruit
law of multiple proportions: (chemistry) law stating that when two elements can combine to form more than one compound the amounts of one of them that combines with a fixed amount of the other will exhibit a simple multiple relation