Nutlet structures of subsection Fragiles of the genus Stachys (Lamiaceae) from Turkey and their systematic applications

Mehmet Cengiz KARAİSMAİLOĞLU,Özal GÜNER

doi:10.3906/bot-1812-31

Abstract

This paper includes the morphological and anatomical characters of the nutlets of 7 endemic species of the subsection Fragiles of the genus Stachys (Lamiaceae) from Turkey and the systematic significance of these characteristics, using one-way analysis of variance and cluster and principal component analyses. Morphological characters such as the dimensions, shapes, colors, and surfaces of the nutlets were studied using light and scanning electron microscopes. The structures and thicknesses of the pericarp and endosperm layers, as well as the sizes of the cotyledon in the nutlets, were anatomically studied. The outcomes revealed that the taxa varyfrom each other in terms of nutlet shape and color. The nutlet dimensions range from 1.31 mm to 3.49 mm in length and from 0.84 mm to 1.95 mm in width. While Stachys longiflora and S. pseudopinardii have the largest nutlets, S. chasmosericea has the smallest. The nutlet surface ornamentation was recorded as 5 types: reticulate, scalariform, reticulate-foveate, ruminate, and rugose. The most common type is reticulate; however, the other ornamentation types are specific for the studied taxa. Anatomically, the structure and thickness of the pericarp parts and the endosperm and the size of the cotyledon are very important characteristics that disclose interspecific relations within the studied taxa. A key is presented for the identification of the examined taxa based on the nutlet properties.

Highlights

The genus Stachys L., one of the largest genera in the family Lamiaceae, comprises approximately 370 species (435 taxa) (Harley et al, 2004; Govaerts, 2015; Akçiçek et al, 2016)
The purpose of this paper is to offer a detailed description of the nutlet morphology and pericarp characters of 7 endemic taxa belonging to the subsection Fragiles of the genus Stachys as a whole, using light microscopy and SEM, and to assess the taxonomic importance of such characters in light of the variations between the studied taxa of the genus
Macromorphological investigations of the nutlets of Lamiaceae have proven beneficial at various levels of the taxonomic hierarchy (Wojciechowska, 1966; Marin et al, 1996; Moon and Hong, 2006)

Summary

Introduction

The genus Stachys L., one of the largest genera in the family Lamiaceae, comprises approximately 370 species (435 taxa) (Harley et al, 2004; Govaerts, 2015; Akçiçek et al, 2016). It is composed of annual and perennial herbs, and small shrubs. In Turkey, the section comprises 22 taxa, with an endemism rate of 72.7% from 2 subsections: Fragiles Rech.f. and Multibracteolatae R.Bhattacharjee. These taxa are suffrutescent saxatile perennials and their stems are fragile at the base. The section is separated by the determined characters from the rest of the sections

Objectives

Methods

Conclusion