The foxglove plant is the main source of this medicine used as a stimulant  in damaged heart tissue
... diuresis, expectoration, wound healing, and be a stimulant; Harmful 
effects: ..... Foxglove is no longer used as a heart medicine because the 
therapeutic dose... [DOC] [TLE] Poisonous plants [PAR] Poisonous plants may be medicinal or food plants used improperly ... in living 
tissues, plants store tannins in isolation to prevent damage to its own ... pain 
relievers, cardiac and respiratory stimulants, muscle relaxants, blood ... also 
used as heart medication.