Dragonhead (Dracocephalum moldavica L.) as an annual, herbaceous, essential oil-generating, spicy aromatic medicinal plant has essential oil at 0.06-0.92% depending strongly on environmental conditions. In order to evaluate the resultant composition of essential oil in herbage of dragonhead samples gown under different conditions, filed experiments were performed at five different areas across Iran (L1: Maragheh, L2: Tehran, L3: Isfahan, L4: Khoy, and L5: Piranshahr). Upon harvesting the plants at full flowering stage, their essence contents were characterized by GC/MS and GC/FID analyses. Results were indicative of significant effect of geographical location on content and composition of the essential oils, with the highest and lowest contents of essential oil observed at Isfahan (63 ml 100 g-1 dried plant) and Maragheh (41 ml 100 g-1 dried plant), respectively. Also, Tehran and Isfahan exhibited the highest essential oil yields (27 and 29 kg ha-1), respectively. Main components of the oil included geraniol, geranial, neryl acetate, geranyl acetate and neral. The geraniol and geranyl acetate were maximal in the plants grown in Tehran followed by those in Isfahan. Evaluation of the essence content showed that, comparing different locations, the widest ranges of variation were related to geraniol (16.3 %), neral (16 %), geranyl acetate (14.26 %), geranial (14.22 %), and β-Pinene (1.7 %). The studied areas had significantly different growth periods, i.e. from sowing to flowering stage. Remarkably, impact of location on sabinene, linalool and neryl acetate contents was minimal, so that these components remained relatively the same in different areas. Findings indicated effectiveness of location on both quantity and quality of essential. In general, as far as essential oil generation was concerned, dragonhead exhibited the best yield in Isfahan. Consequently, agro-climatic zoning and appropriate location selection can be seen as very important strategies for optimizing
