Trichomes morphology of stachys lavandulifolia vahl. (Labiatae) of Iran

Stachys Vahl. is a genus about 300 species of annual and perennial herbaceous plants and shrubs in the family Lamiaceae. The distribution of the genus covers Europe, Asia, Africa, and Australia. Stachys lavandulifolia Vahl. is one of these genus members, which widely distributed in Iran. In this study, in order to compare the effect of different environmental parameters on trichomes morphology and distribution, the trichomes micromorphology of three different geographical populations(Tafresh, Kharaghan and Nobaran) of S. lavandulifolia were surveyed by scanning electron microscopy and light microscopy of leaves and stems.24 trichomes type were described. These can be divided to glandular and non-glandular trichomes. Glandular hairs can be divided to sessile and stalked trichomes. Stalked glandular hairs were of 3 main types: Peltate, Capitate and Digitiform. Sessile glandular trichomes were 2 celled and universally were present on leaves of Tafresh populations. Digitiform trichomes were of 2 types: 1-2 celled, which can be found on stems and leaves of Kharaghan and Nobaran populations. Long-stalked capitates trichomes with a bicellular base and long-stalked capitates with a bicellular neck and long-stalked capitates trichomes with bicellular base and bicellular head were restricted to Nobaran samples. Non-glandular trichomes can be divided into three main groups: simple (unbranghed) hears, two and three armed hears and stellate trichomes. Simple hears were presented as: long and short 1-3celled trichomes were universally presents all populations. Stellate trichomes were presented as: 4, 5, 6, 8, and 16 arms which were different in cell number at arms. The results of this study show that ecologic and edaphically conditions have impact on composition, dispersion and diversity of plant trichomes and lead to interpopulation variety in the trichomes of this species.