Nutlet micromorphology and its taxonomic utility in Lamium L. (Lamiaceae)

Abstract

This paper presents results of examination of fruit surface in the genus Lamium L. (Lamiaceae) using scanning electron microscopy (SEM). The purpose of this study was to define new features that differentiate taxa difficult to identify on the basis of macromorphological features, such as species of hybrid origin and subspecies within Lamium. The results of our research show that the SEM analysis of fruit surface allowed defining new diagnostic features for almost all studied representatives of the genus Lamium except for L. confertum from L. coutinhoi and L. album subsp. album from L. album subsp. barbatum. The most useful feature in distinguishing the examined species was cuticle striation. I turn, the type of secondary sculpturing of the cell walls divided the species studied into two main groups. One of them consisted of four taxa (L. album, L flexuosum, L. garganicum, L. orvala) with thickenings of the cell walls in the form of irregular ridges and tubercles. The other one comprised all the remaining species, with cell wall thickenings forming regular papillae. The only species which could not be qualified to any of these groups was L. moschatum. The obtained results demonstrated also high similarity of L. galeobdolon to the remaining species of Lamium, especially L. flexuosum and L. orvala. This observation provides an argument for the inclusion of L. galeobdolon to the genus Lamium.

Pogostemon nudus sp. nov. (Lamiaceae) from Thailand

“…Furthermore, a number of taxonomic studies suggest that the nutlet contributes valuable taxonomic information (Barthlott , , Ryding , , Marin et al , Salmaki et al , Moon et al , Krawczyk and Glowacka ). In this study, characters of the nutlet were investigated and compared in terms of width, length, length and width ratio, shape and surface sculpturing (Table ).…”

“…Therefore, nutlets can provide valuable taxonomic criteria at various taxonomic levels (Barthlott ). Consequently, Lamiaceous nutlet morphology and surface ornamentation has been increasingly used in recent taxonomic studies (Ryding , , Marin et al , Salmaki et al , Moon et al , Krawczyk and Glowacka , Paton et al ). Here, we investigated leaf epidermal features and nutlet morphology of the new taxon relative to similar species found in Thailand in order to support the species identification.…”

Nutlet micromorphology of the genus Marrubium L. and allies and its systematic implication (Lamiaceae: tribe Marrubieae)

“…Studies on nutlet micromorphology within Lamiaceae showed that nutlets features e.g., shape, morphology of the abscission scar and surface sculpturing, were potentially useful at different taxonomic levels (e.g. Demissew & Harley, 1992;Marin et al, 1994;Ryding, 1995;Oran, 1996;Ryding, 1998;Salmaki et al, 2008;Moon et al, 2009;Satil et al, 2012;Krawczyk & Głowacka, 2015;Eyvaz?zadeh Khosroshahi & Salmaki, 2018). Among different nutlet characters, type of sculpturing has been considered to be taxonomically most important (Oran, 1996;Kahraman et al, 2011), however, color, size and shape of nutlets were considered unimportant, either because they did not vary or the variation was random or too great (Oran, 1996).…”

Nutlet morphology in the tribe Elsholtzieae (Lamiaceae)

“…Nutlet morphology in Lamiaceae has emerged as a vital source of systematics information in taxonomy (Moon et al 2009a, Ryding 2010a, Satil et al 2012, Krawczyk and Głowacka 2015, Ecevit-Genç et al 2017, Amirmohammadi et al 2019). Because surface sculpturing of the nutlets tends to be less affected by environmental pressures than other morphological characteristics, such as leaf micromorphology (Moon et al 2009b), floral micromorphology (Jang et al 2014) and crystal types in calyces (Ryding 2010b), nutlet micromorphological characters enable taxa to be distinguished or affinities discovered (Moon et al 2009a, Krawczyk and Głowacka 2015, Ecevit-Genç et al 2017. A number of Lamiaceae species have been studied extensively in terms of nutlet surface sculpturing, and in combination with phylogeny at the tribe level (Budantsev andLobova 1997, Moon et al 2009a).…”