Foxglove leaves are used to produce digitalis medicines, including cardiac glycosides used in heart care. Foxglove refers to plants in the genus Digitalis, particularly Digitalis purpurea and Digitalis lanata. Their leaves contain compounds such as digitoxin and digoxin that affect the force and rhythm of heart contractions.
The medical story was developed by English physician William Withering, who described foxglove’s usefulness for treating dropsy in 1785. Dropsy, now understood in many cases as fluid retention associated with heart failure, could improve because these compounds increase the strength of cardiac contraction and influence the heart rate.
The term digitalis can mean the plant, its extracts, or the broader family of medicines derived from it. Modern digoxin has commonly been obtained from Digitalis lanata rather than only the common purple foxglove. That distinction does not change the quiz answer: foxglove is the familiar plant source.
Foxglove is also highly poisonous outside carefully controlled medical use. Its narrow therapeutic index means the useful dose is close to the toxic dose; nausea, visual disturbances, dangerous heart rhythms, and cardiac arrest can result from poisoning.