The study was conducted in North-Central Anatolia under semi arid conditions. Seeds of 18 basil landraces (O. basilicum L.) were collected from local farms and home gardens in Turkey. To examine essential oil composition of the basil landraces without environmental influences, the plants were grown under identical (same environmental and soil conditions) conditions. Seeds were sown on a medium (1:1:1 washed sand, horse manure and field soil) in greenhouse conditions on March 25, 2003. Seedlings were grown until the 3-5 leaf stage. The seedlings were transplanted into pilots in the Gaziosmanpasxa University Experimental Research Station on May 15, 2003. The plants were harvested at the full blooming stage and dried at 35 ℃ for essential oil isolation.

Variation of essential oils in the landraces was subjected to cluster analysis, and seven different chemotypes were identified. They were (1) linalool, (2) methyl cinnamate, (3) methyl cinnamate/linalool, (4) methyl eugenol, (5) citral, (6) methyl chavicol (estragol), and (7) methyl chavicol/citral. Methyl chavicol with high citral contents (methyl chavicol/citral) can be considered as a 'new chemotype' in the Turkish basils.