Trichomes on Vegetative and Reproductive Organs of Endemic Ballota macrodonta (Lamiaceae)

Abstract

The morphological features and distributions of trichomes on both vegetative and reproductive organs of endemic Ballota macrodonta were examined in this study. The species has limited distrubution in Türkiye and is endemic Iranian Turanian element. In this taxon, different trichome types were seen and these trichomes were divided into two main groups. The first group forms eglandular trichomes, the other group forms glandular trichomes. Two types of eglandular trichomes were obtained on the vegetative and reproductive organs of the taxon: simple unbranched and branched. Stellate type of branched eglandular trichomes were seen more frequently on the lower surface, margins, veins of leaves, corolla, and outer part of calyx, while long unicellular, bicellular, tricellular and multicellular types of simple unbranched eglandular trichomes were seen more frequently on all the organs of this taxon. Glandular trichomes were categorized as capitate with different stalk lengths and one–two head cells and peltate with four–eight secretory cells. According to number of stalk cells, capitate trichomes were grouped into as unicellular, bicellular, tricellular and multicellular trichomes. The capitate ones were seen nearly on all organs of B. macrodonta. Peltate trichomes were rarely found on the stem, upper surface of leaf and corolla, while these trichomes were densely found on the surface of the calyx. It was emphasized that both simple unbranched and stellate eglandular trichomes could be used as valuable characters in the classification of this species.