The ethnobotany, leaf anatomy and major essential oil compounds of Leysera gnaphalodes (Asteraceae), a poorly known aromatic herbal tea endemic to southern Africa

Abstract Leysera gnaphalodes (L.) L. (viz., Leyssera gnaphalioides L.) is an aromatic, medicinal Cape herbal tea endemic to southern Africa. The plant is known by many different vernacular names, most relating to its use as tea: geelblommetjiestee, duinetee(bossie), skilpadtee(bossie), teringtee(bossie), hongertee and geeltee. According to historical literature and recent ethnobotanical surveys in the Little Karoo, this aromatic shrublet is a treatment for numerous respiratory ailments, especially ‘tering’ (tuberculosis). Previous studies have reported the presence of several diterpenes and triterpenes, but the main essential oil compounds have remained unknown. These were identified as α-pinene, β-pinene, p-cymene, carvacrol and bicyclogermacrene. Multicellular glandular trichomes are present on the leaf surface, which may be the site of oil production and/or accumulation. Leysera gnaphalodes has been reported to exhibit significant anti-mycobacterial activity against three Mycobacterium micro-organisms. The traditional claim of its efficacy as a treatment against tuberculosis, as reflected by the common name teringtee (‘tuberculosis tea’) therefore appears plausible. This activity seems to be primarily associated with the presence of the well-known pentacyclic triterpenoids, oleanolic acid and ursolic acid.