Trichome morphology of the tribe Pogostemoneae (Lamioideae; Lamiaceae)

The Pogostemoneae taxa are characterized by having posterior lip often short, stamens often long exserted, filaments often bearded and nutlets often small. A comprehensive investigation of the trichome morphology of tribe Pogostemoneae was studied to determine the usefulness of these characteristics for systematic purposes. We have investigated the distribution and morphology of trichomes of stems, leaves, and calyces in ۱۰ taxa of ۹ genera of Pogostemoneae using light microscopy and Scanning Electron Microscopy. Two basic types of trichomes can be distinguished: non-glandular and glandular. The non-glandular trichomes can be subdivided into subtypes: simple (i.e. short, long, and extremely long trichomes) and branched. Capitate trichome (that subdivide to sessile, short-stalked, and stalked) and peltate constitute two subtypes of glandular trichomes. Simple short non-glandular and sessile glandular trichomes are the most common types of trichomes in the tribe. Leucosceptrum, Rostrinucula, and Comanthosphace are characterized by branched trichomes. Peltate trichomes were observed only in Pogostemon benghalensis among all the species that were studied. Our results showed that the presence or absence of trichomes and types of them are important morphological traits and can be considered as diagnostic properties in the Pogostemoneae tribe.

کلیدواژه ها:

Classification ، Pogostemoneae ، Taxonomy ، Trichome morphology