Which plant is the source of the cardiac drug digitalis?

Foxglove is the plant source of the cardiac drug digitalis. The name refers to cardiac glycosides first obtained from plants in the genus Digitalis, especially foxgloves such as Digitalis purpurea and Digitalis lanata.

These compounds can strengthen the force of heart contractions and help control certain abnormal heart rhythms. English physician William Withering documented foxglove’s medicinal use for dropsy, an old term associated with fluid retention, in 1785.

Foxglove is highly poisonous as well as medicinal. Its leaves, flowers, and seeds contain compounds such as digoxin and digitoxin, and the difference between a therapeutic dose and a dangerous dose can be very small. Modern digoxin production has particularly been associated with woolly foxglove, Digitalis lanata.

The common mix-up is treating “digitalis” as the name of one single chemical or one single species. In medicine, it can describe a group of cardiac glycosides or preparations containing them, while foxglove is the familiar plant answer accepted by a fair quizmaster.