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Thymbra spicata L. var. spicata is grown naturally in semi-arid climatic conditions of Turkey. The seeds of wild populations collected from various regions were cultivated under arid climatic conditions of Diyarbakır in South East Anatolian region of Turkey. Components of hydrodistilled essential oils obtained from air dried aerial parts of T. spicata were identified and compared using gas chromatography/mass spectrophotometer.Fresh herbage yields of populations ranged 4925 kg ha-1 to 13275 kg ha-1, dry herbage yield varied between 2035 to 4782 kg ha-1 and dry leaf yield ranged 1347 kg ha-1 to 3364 kg ha-1. Essential oil contents of T. spicata populations in dry herb ranged 2.25% to 4.65%. The total oil content of plants and the percentage contribution of the major oil constituents, carvacrol, γ-terpinene and p-cymene, varied remarkably among localities. The highest carvacrol content was found in the population collected from Diyarbakir-Dicle (97.9%). The results indicated that agronomic characteristics, essential oils and chemical compositions of T. spicata are affected by environmental, genetic and agronomic practices under cultivation conditions.Keywords: Thymbra spicata L. var. spicata, populations, cultivation, essential oil, carvacrol