Taxonomic significance of seed‐coat microsculpturing in Noccaea Moench and Thlaspi L. (Brassicaceae: Coluteocarpeae, Thlaspideae)

Abstract

We studied seeds of 25 species of Noccaea and 3 species of Thlaspi s.s. from Europe, southwestern Asia and northern Africa using scanning electron microscopy (SEM). Macro‐ and micromorphological characters, including seed shape, the size and shape of epidermal cells, anticlinal boundaries, outer periclinal cell walls and the outlines of outer cell walls were recorded. Two types of anticlinal cell wall boundaries were recognised and 5 different shapes of outer periclinal walls are described. The secondary sculpture of the cell walls varies from smooth to striate, micro‐papillate to finely foled and rugulate. The epicuticular wax comes in platelets in all the species. SEM examinations at higher magnifications revealed 5 types of seed surface sculpture: colliculate, reticulate, mixed (colliculate‐reticulate), verrucate and foveolate in Noccaea, in addition to ribbed and reticulate patterns in Thlaspi s.s. SEM studies of the taxa showed that the seed patterns are species‐specific and support a clear distinction between Noccaea and Thlaspi. However, some species of Noccaea cannot be separated based on seed size and shape, but may only be identified to their groups. Micromorphological features of the seed surface are thus of great value, both for the differentiation between the genera Noccaea and Thlaspi and for the species‐level taxonomy. A key to the identification of the investigated taxa based on the micromorphological characters is provided.

Comparative anatomy and pollen morphology of two endemic Noccaea species (Brassicaceae) and their taxonomic significance

“…Özüdoğru (2018) stated that seed surface sculpture was regulate in Noccaea rosularis Al-Shehbaz. The general seed coat type of N. granatanse Boissier & Reuter and N. perfoliata Al-Shehbaz was reticulate (Antkowiak et al, 2018). The outcomes of this study are in agreement with the general seed surface characteristics of Noccaea.…”

“…Noccaea is systematically complicated and these problems have not been fully resolved yet. Especially in recent years, in addition to taxonomic features, anatomy, pollen morphology and seed micromorphology have been used extensively for generic delimitation of the Brassicaceae family (Farouji et al, 2018;Antkowiak et al, 2018;Çilden and Zare, 2019).…”

“…In previous studies, it was stated that the dominant type of seed surface sculpture in Brassicaceae was reticulate (Moazzeni et al, 2007;Tantawy et al, 2004). Antkowiak et al (2018) identified five types of seed surface sculpture as colliculate, reticulate, mixed (colliculate-reticulate), verrucate and foveolate in Noccaea species and stated that the collicate pattern was the dominant surface sculptural pattern of Noccaea. Özgişi et al (2018c) reported that surface ornamentation of N. birolmutlui as colliculate.…”

Numerical analyses of seed morphology and its taxonomic significance in the tribe Nigelleae (Ranunculaceae)

“…Seed morphological characters have been considered significant traits for distinguishing among all taxonomic ranks in different plant families (Barthlott 1981, Arroyo-Cosultchi et al 2006, Fagundez and Izco 2011, Antkowiak et al 2018, Ghimire et al 2018). In addition, seed coat morphology, especially micromorphology, have provided useful taxonomic information for different genera of Ranunculaceae (Cappelletti and Poldini 1984, Karcz and Tomzcok 1987, Luo et al 2005, Dadandı et al 2009, Wang et al 2009, Antkowiak et al 2010, Emadzade et al 2010, Heiss et al 2011, Ghimire et al 2015, 2016.…”

Seed variability of Sisymbrium polymorphum (Murray) Roth (Brassicaceae) across the Central Palaearctic

“… Vaughan and Whitehouse (1971) studied the macro- and micromorphology of seeds within 90 genera, including about 200 species of Brassicaceae . Moreover, Kasem et al (2011) and Antkowiak et al (2018) paid particular attention to the relationship between the seed structure and the taxonomy of selected species from this family, for example, Noccacea spp. and Thlaspi spp.…”