Buchu, Or Buka Leaves, the produce of several shrubby plants belonging to the genus Barosma (nat. order Rutaceae), natives of the Cape of Good Hope. The principal species, B. crenulata, has leaves of a smooth leathery texture, oblong-ovate in shape, from an inch to an inch and a half in length, with serrulate or crenulate margins, on which as well as on the under side are conspicuous oil-glands. The other species which yield buchu are B. serratifolia, having linear-lanceolate sharply serrulate leaves, and B. betulina, the leaves of which are cuneate-obovate, with denticulate margins. They are all, as found in commerce, of a pale yellow-green colour; they emit a peculiar aromatic odour, and have a slightly astringent bitter taste. Buchu leaves contain a volatile oil, which is of a dark yellow colour, and deposits a form of camphor on exposure to air, a liquid hydro-carbon being the solvent of the camphor within the oil-glands. There is also present a minute quantity of a bitter principle. The leaves of a closely allied plant, Empleurum serratulum, are employed as a substitute or adulterant for buchu. As these possess no glands they are a worthless substitute. The British Pharmacopoeia contains an infusion and tincture of buchu.
The former may be given in doses of an ounce and the latter in doses of a drachm. The drug has the properties common to all substances that contain a volatile oil. The infusion contains very little of the oil and is of very slight value. Until the advent of the modern synthetic products buchu was valued in diseases of the urinary tract, but its use is now practically obsolete.