Agathosma is a genus of about 140 species of flowering plants in the family Rutaceae, native to the southern part of Africa. Common names include Buchu, Boegoe, Bucco, Bookoo and Diosma. Buchu formally denotes two herbal species, prized for their fragrance and medicinal use despite their toxicity. In colloquial use however, the term (see Boegoe) is applied to a wider set of fragrant shrubs or substitutes.

They are small shrubs and subshrubs, mostly with erect woody stems reaching 30–100 cm tall, but low-growing and prostrate in some species. The leaves are usually opposite, ericoid, often crowded, simple, entire, from 0.5-3.5 cm long. The flowers are produced in terminal clusters, 0.7–2 cm diameter, with five white, pink, red or purple, petals.

Many of the species are highly aromatic, and the genus name means "good fragrance". Some species of the genus are used as herbal remedies.