What plant is the source of the heart medication digitalis?

The plant that supplies the heart medication digitalis is foxglove. In particular, Digitalis purpurea, the common foxglove, contains cardiac glycosides such as digitoxin and digoxin, compounds that can make heart contractions stronger and help regulate the heartbeat.

Foxglove is native across much of temperate Europe and is a biennial plant: it forms a leafy rosette in its first year, flowers in its second, then dies after producing seeds. Its medicinal story was advanced by English physician William Withering, who described foxglove’s usefulness for “dropsy” in 1785. Dropsy, now understood mainly as edema associated with heart failure, could improve when the drug increased circulation and urine production.

The name digitalis comes from the Latin digitus, meaning “finger,” a reference to the finger-like shape of its bell-shaped flowers. A common mix-up is treating “digitalis” as the plant’s ordinary common name; it also refers to medicines containing cardiac glycosides. Foxglove itself is highly poisonous, and the therapeutic dose is close to a toxic dose, so preparations must be medically controlled. Modern digoxin is commonly obtained from Digitalis lanata, another foxglove species.