Agathosa Betulina (previously Barosma Betulina) is a flowering plant in the family Rutaceae, native to the lower elevation mountains of western South Africa, where it occurs near streams in fynbos habitats.The leaves are opposite, rounded, about 20 mm (0.79 in) long and broad.
The two primary chemical constituents of the oils of A. betulina are isomenthone and diosphenol.