Leaves of the plant Agathosma betulina or sometimes Barosma betulina are called Buchu leaves. These oil-bearing plants are native to South Africa, where they are harvested for their medicinal properties.
The main active components are the volatile oils such as l-pulegone, isopulegone, thiophenol (buchu camphor) and many others.
Historically, Buchu leaves have been reported to have diuretic, urinary antiseptic activity, and as a tonic for the genitourinary system. It is still used primarily for these indications, although "Unapproved" for such by the German Commission E.