The chemical composition of the aerial parts essential oil of Heldr. (Lamiaceae) growing in Kythira island (Greece).

is a large genus of economically important plants belonging to Lamiaceae family that includes about 300 species as annual or perennial herbs. Several species of this genus are extensively used in various traditional medicines. In the present study the chemical composition of the essential oil from aerial parts of Heldr., a very rare plant, belonging to Section , endemic of South Greece and collected in the island of Kythira, was analysed by GC-MS. No one reports have been previously published on this species. The result showed the presence of large quantity of diterpenoids with manoyl oxide (22.1%), as the most abundant component. Other metabolites present in high quantity were -nerolidol (18.5%), -caryophyllene (11.0%) and germacrene D (8.1%). Chemotaxonomic considerations with respect all the other oils of taxa, belonging to the same section studied so far, were carried out.