Aspirin and Quinine come from trees, and digitalis, a medicine used in heart failure is extracted from the Foxglove.

BBC: 'Natural doesn't always mean best'

Consider foxglove, whose active chemicals digoxin and digitoxin are used in the formulation of drugs to treat congestive heart failure.

WSJ: Big Pharma's Real Roots | Wild Medicine | New York Botanical Garden | By Joanne Kaufman