Buchu belongs to the genus Agathosma, in the family of Rutaceae. These plants are native to the southern parts of Africa. A crenulata and A. betulina are endemic to the Western Cape.

Buchu is a compact shrub with scented leaves, flowering from autumn to spring.  The numerous oil glands on the leaves produce an aromatic scent which deter pests. By releasing these oils on hot days a vapour layer is formed which helps with water retention, reducing excess transpiration.