Leaf indumentum in some Turkish species of Teucrium (Lamiaceae)

Abstract

Trichome micromorphology can be used as a discriminating character in the separation of species and subspecies. The micromorphological characteristics of foliar trichomes from five Teucrium taxa (T. scordium subsp. scordium, T. sirnakense, T. chasmophyticum, T. andrusi and T. spinosum) were investigated by scanning electron microscope. Seven types of trichomes were identified, including glandular and non-glandular. The glandular trichomes were recorded in three types; short clavate, long clavate, and subsessile. The non-glandular trichomes were identified with four types; unicellular thin-walled, 2(5)-celled thin-walled, 3-7(11)-celled flexuose, elongated thin-walled and 2-celled thick-walled trichomes. Generally, the trichome types were similar on both sides of the leaves, except in T. spinosum. Subsessile glandular trichomes were the most common type and were occurred in all the investigated species. Also clavate glandular trichomes were found in all the species, except T. scordium subsp. scordium. All trichomes were distinctively thick-walled, whereas thin-walled trichomes were observed in only T. chasmophyticum species. The leaf micromorphology of T. sirnakense and T. chasmophyticum has also been reported in detail for the first time in this study.