Pollen morphology and systematical contribution of some Onosma (Boraginaceae) taxa distribution in Turkey

A reappraisal of the genus Megacaryon (Boraginaceae, Lithospermeae) based on molecular, morphological, and karyological evidence

“…Although relationships in Echium s.l. were largely known thanks to previous phylogenetic studies focusing on it (B€ ohle et al, 1996;Hilger & B€ ohle, 2000), old-world Lithospermeae (Cecchi & Selvi, 2009) or Boraginaceae (Cohen, 2014;Mansion et al, 2009;Weigend et al, 2013), our findings add elements that may lead to a better definition of the generic units in this clade and allow us to resurrect Megacaryon.…”

“…Our observations confirmed this species and Pontechium maculatum to be palynologically close to the genera mentioned above and to Onosma, in their small-sized, heteropolar (pear-shaped) grains with three narrow ectoapertures free at ends, each provided with a circular endoaperture close to the broader pole. Onosma and Echium differ mainly in the tectum ornamentation, which is punctate-perforate, more or less scabrate to rugulate in the former (see also Binzet, Erkara, € Ozler, & Pehlivan, 2014) and reticulate, microreticulate to foveolate in the latter. This character has been considered 'evolutionarily more advanced' (Liu et al, 2010), while M. orientale, and apparently Pontechium as well, are clearly closer to Onosma in their nearly smooth tectum that may represent the plesiomorphic condition in the Onosma-Echium s.l.…”

“…Habit, life cycle and other vegetative characters are widely variable. The herbaceous habit is exclusive in the primary diversity centre in the west Mediterranean, continental Europe, and western Asia, while the woody, shrubby habit is characteristic of most Macaronesian endemic species that originated from mainland ancestors through a massive radiation in the Canary, Cape Verde, and Madeira islands (B€ ohle, Hilger, & Martin, 1996;Mansion, Selvi, Guggisberg, & Conti, 2009).…”

Molecular phylogeny and divergence times of Onosma (Boraginaceae s.s.) based on nrDNA ITS and plastid rpl32‐trnL(UAG) and trnH–psbA sequences

“…This species appears to be clearly distinct from Onosma and more closely related to Alkanna, confirming the findings of previous molecular studies (Cecchi and Selvi 2009, Weigend et al 2009, Nazaire and Hufford 2012, Cohen 2013, Selvi et al 2017, except for the ISSR analysis of Mehrabian et al (2011). Its close affinity with Alkanna is also supported by morphological traits such as subhorizontally incurved nutlets with a small stiphate areole, gynobase with four cartilaginous cushion-like lobes and ovoid, tricolporate pollen grains (Johnston 1954, Cohen 2013, Binzet et al 2014.…”

“…The vast majority of Onosma, therefore, appear to form a monophyletic group, to which we will henceforth refer as Onosma s.s. This clade is characterized by a mixture of morphological traits including free or basally coherent anthers, glabrous or hairy nectariferous annulus, usually (Riedl 1978, Zhu et al 1995, Azizian et al 2000, Liu et al 2010, Mehrabian et al 2012, Binzet et al 2014. It also has various basic chromosome numbers, x = 6, 7, 8, 10, 11 .…”