N. Razazi - Department of Genetics and Plant Breeding, Ahvaz Branch, Islamic Azad University, Ahvaz, Islamic Republic of Iran.
A. A. Jafari - Research Institute of Forests and Rangelands, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Islamic Republic of Iran.
Z. Khodarahmpour - Department of Production and Plant Genetics, Shoushtar Branch, Islamic Azad University, Shoushtar, Islamic Republic of Iran.
S. Sadat - Department of Genetics and Plant Breeding, Ahvaz Branch, Islamic Azad University, Ahvaz, Islamic Republic of Iran.

The genus Stachys L., (Lamiaceae family) has several spicy and aromatic species. In order to investigate the diversity of aerial biomass, morphological traits, and essential oil yield, ۴۷ populations out of five species including S. lavandulifolia, S. laxa, S. inflata, S. germanica and S. byzantina were evaluated during two years, at a research farm in Khorramabad, Iran. The traits such as plant height, leaf length, leaf width, stem number, stem diameter, vegetation cover, ۱,۰۰۰ seed weight, and aerial dry (DM) yield in all ۴۷ populations were measured. The essential oil was extracted using the hydrodistillation method with a Clevenger-type apparatus. The essential oil compounds were detected using GC and GC/MS. Data were analyzed using nested ANOVA with Minitab۱۶ software. The results showed that both S. germanica and S. byzantina had higher aerial biomass than the other species. The Saveh and Tehran populations of S. inflata, the populations of Qazvin and Qorveh in S. lavandulifolia, and the populations of Ardebil and Semirom in S. Byzantine were superior to the others for the measured traits. For essential oil yields (w/w), the highest and lowest values were ۲.۰ and ۰.۸%, obtained in S. byzantina and S. lavandulifolia, respectively. Phytochemical analyses of S. lavandulifolia identified ۴۳ compounds. The main compounds were β-eudesmol (۳.۴۸%), germacrene-D (۴.۵۹%), δ-cadinol (۴.۶۹%), bicyclogermacrene (۶.۸۵%), δ-cadinene (۹.۶۹%), spathulenol (۱۰.۰۸%) and α-cadinol (۱۲.۸۶%). S. lavandulifolia, with early maturity and higher essential oil, was recommended for domestication and breeding of improved varieties.

Phytochemical trait, S. byzantine, S. germanica, S. inflata, S. lavandulifolia, S. laxa.