Systematic importance of pollen morphological features of selected species from the genus Rosa (Rosaceae)

Abstract

The aim of this study is verification of the taxonomic usefulness of the pollen grain features studied, based on pollen morphology of 32 wild species from all 4 subgenera and all 10 sections of the genus Rosa, mainly for delimitation of subgenera, sections, and species. The measurements and observations were carried out with both light microscopy and scanning electron microscopy. Only correctly formed pollen grains (30 per specimen) were measured, and 960 pollen grains were examined in total. They were analyzed for 14 quantitative features of pollen grains and exine sculpturing and the following qualitative ones: outline, shape, and operculum structure. Our study revealed that the diagnostic features of pollen grains studied were: exine sculpture, length of polar axis, and pollen shape (P/E ratio). On the basis of the above characters, five species were isolated and the remaining ones were included in several groups isolated on the basis of exine sculpture types. The following three exine sculpture types occurred in the species studied: granular-verrucate (in R. stellata), striate-psilate (in R. multibracteata and R. multiflora), and striate (the remaining species). R. banksiae is characterized by small pollen grains, while R. setigera has strongly elongated pollen with P/E ratio [1.5. Exine sculpture features considered to be diagnostic should be treated as auxiliary because they fail to differentiate individual species, although they can be helpful in distinguishing groups of species of similar exine sculpture. The arrangement of the species examined on a dendrogram only slightly corroborates division of the Rosa genus into subgenera and sections currently adopted in taxonomy (Rehder 1940). An interesting result was reported for the species studied from the Caninae (R. agrestis, R. canina, R. dumalis, R. jundzillii, and R. rubiginosa) section which, despite hybrid nature, with the exception of R. villosa, grouped in the same, most separated group of species.

Investigation on the pollen morphology of traditional cultivars of Prunus species in Sicily

“…This latter species, shows the highest diversity of the observed parameters, probably because of its hybrid origin according to the hypothesis of Zeven & De Wet [33]. Moreover, in the subfamily of Prunoideae the exine structure could be considered an auxiliary diagnostic character, as also reported for the genus Rosa [17], to increase the number of the taxonomical characters that can be utilized for discrimination of the species.…”

“…They thought the pollen size to be the least reliable feature and they related it to the comparatively frequent occurrence of hybrid and polyploid species in this family. In the subgenera Sorbus, Chamaespilus and Torminaria belonging to the genus Sorbus, pollen morphology corresponds with their systematic classification [16], while in the genus Rosa, a recent study showed that the exine sculpture can be helpful in distinguishing groups of species although only slightly corroborates division of the genus in subgenera and sections [17].…”

Comparison of pollen grain morphological features of selected species of the genusCrataegus(Rosaceae) and their spontaneous hybrids

“…All samples were acetolysed according to the method described by Wrońska‐Pilarek (, ) and Wrońska‐Pilarek & Jagodziński (). The acetolysing mixture was made up of nine parts of acetic acid anhydride and one part of concentrated sulphuric acid, and the process of acetolysis lasted 2.5 min.…”

Combined LM and SEM study of the middle Miocene (Sarmatian) palynoflora from the Lavanttal Basin, Austria: part IV. Magnoliophyta 2 – Fagales to Rosales

“…The basic pollen morphology of all three rosaceous subfamilies (see Potter et al 2007) and many genera/species of the tribes and subtribes within Rosaceae have been studied to some extent. Pollen types of the subfamily Rosoideae have been studied using mostly LM and SEM by Huang (1972), Hebda et al (1988aHebda et al ( , 1988b, Hebda and Chinnappa (1990), Jones et al (1995), Wang et al (1995), Beug (2004), Tahir (2005), Fujiki and Ozawa (2007), Chung et al (2010), Li et al (2011a), Miyoshi et al (2011), Wrońska-Pilarek (2011), Wrońska-Pilarek and Jagodziński (2011), Wrońska-Pilarek et al (2012, Perveen and Qaiser (2014) and Faghir et al (2015). The subfamily Dryadoideae has been studied by Hebda et al (1988b) and Beug (2004).…”