Morphology of pollen grains of Weigela floribunda (Caprifoliaceae): application in taxonomy

The aim of this research was to provide detailed quantitative and qualitative characteristics on pollen grains of Weigela floribunda (Siebold & Zucc.) K. Koch (Caprifoliaceae) as applied for taxonomy. Pollen morphology of W. floribunda was studied using both light microscopy and scanning electron microscopy. Pollen grains are 3-porate, rarely 4-porate, suboblate to spheroidal (P/E=0.80–1.05); in equatorial view elliptic or circular, in polar view circular or subcircular; medium- or large-sized (P=42.56–61.18 µm, E=42.56–66.50 µm). Pores are circular with distinct or indistinct margins and distinct annuli. Exine sculpture is echinate-microechinate-nanoechinate. Pollen grains of W. flori- bunda were analyzed for the first time in the present study.

Flowering Biological Characteristics of Camellia weiningensis Y.K. Li.

This study aimed to investigate the flowering biological characteristics, floral organ characteristics, and pollen morphology of Camellia weiningensis Y.K. Li. These features of adult C. weiningensis plants were observed via light microscopy and scanning electron microscopy (SEM). Pollen viability and stigma receptivity were detected using 2,3,5-triphenyltetrazole chloride (TTC) staining and the benzidine–hydrogen peroxide reaction method. C. weiningensis is monoecious, with alternate leaves and glabrous branchlets. Its flowering period lasts 2 to 4 months, and the flowering time of individual plants lasts ≈50 days, with the peak flowering period from the end of February to the middle of March. It is a “centralized flowering” plant that attracts a large number of pollinators. Individual flowers are open for 12 to 13 days, mostly between 1230 and 1630 hr, and include four to six sepals, six to eight petals, ≈106 stamens, an outer ring of ≈24.6-mm-long stamens, an inner ring of ≈13.4-mm-long stamens, one pistil, and nine to 12 ovules. The flowers are light pink. The style is two- to three-lobed and 16.6 mm long, showing a curly “Y” shape. The contact surface of the style is covered with papillary cells and displays abundant secretory fluid and a full shape, facilitating pollen adhesion. The pollen is rhombohedral cone-shaped, and there are germ pores (tremoids). The groove of the germ pore is slender and extends to the two poles (nearly reaching the two poles). The pollen is spherical in equatorial view and trilobate in polar view. The pollen vitality was highest at the full flowering stage, and the stigma receptivity was greatest on days 2 to 3 of flowering. The best concentration of sucrose medium for pollen germination was 100 g/L. The number of pollen grains per anther was ≈2173, and the pollen-to-ovule ratio was 23,034:1. C. weiningensis is cross-pollinated. Seventy-two hours after cross-pollination, the pollen tube reached the base, and a small part entered the ovary. The time when the pollen tube reached the base after pollination was later than that in commonly grown Camellia oleifera. The results of this study might lay an important foundation for the flowering management, pollination time selection, and cross-breeding of C. weiningensis.

Comparative palynomorphological study of two species in the valley of Zagoria, Gjirokastra, Albania

In this study there are demonstrated for the first time in albanian literature the palynomorphologic characteristics of two types of plants (Centaurea epirota and Viola epirota), collected in Zagoria valley, Gjirokastra region, in Albania. To carry out the study, light microscopy was used and it was concluded that the pollen grains of Centaurea epirota were 3 colporate, isopolar, with radial symmetry. In the polar view, the pollen grains have a circular triangular shape while in the equatorial view they have a compressed oval shape. Exine appeared scabrate. Viola epirota consisted of 3-4 colporate, sometimes even 5 colporate pollen grains. In the polar view, the pollen grains had a circular shape of 3 or 4 angles, sometimes even 5 angles while in the equatorial view they had an elliptical shape. Exine appeared granulate. To see the impact of ecological factor and the method of laboratory processing of pollen grains, the size of the new species studied was compared with the size of the pollen grains of Centaurea cyanus and Viola alba, Viola odorata and Viola arvensis, taken from the native literature.

Pollen Viability and Germinability of Gamma Irradiated M4 Lines of Sesame

Pollen viability and germinability are indispensable criteria in plant breeding programmes. This research evaluated eleven M4 mutant lines of gamma irradiated sesame (Sesamum indicum) for some pollen parameters. Seeds were obtained from the Department of Plant Biology, Federal University of Technology, Minna and were raised to maturity alongside their respective checks in a randomized complete block design (RCBD). The field experiment was conducted at the experimental field of the Upper Niger River Basin Development Authority, Minna. Pollen viability and diameter were determined using standard procedure. The germinability test was done using three different sucrose concentrations (10 %, 20 % and 30 %) with 1 % nutrient agar solution. The results revealed that all the M4 mutant lines had adequate pollen viabilities (over 80%) with ML-10 having the highest (97.56 %) viability followed by ML-7 (95.61 %), ML-8 (95.01 %) and Check-2 (95.60 %). The highest pollen germinability was recorded at 20 % sucrose concentration for all the mutant lines with line ML-7 (39.70 %) having the highest percentage. Check-1 at 10 % sucrose concentration recorded the least percentage (11.46 %) across the concentration and treatments. Highest pollen diameter (169.52μm) was recorded in Check-1. Suboblate shapes with 10-13 colpi was observed in all the mutant lines and the checks. Pollens from all the lines comprised of circular and elliptic pollens except in ML-7 and the checks where the pollens were solely circular in polar view. The study revealed that gamma-irradiation could be a reasonable tool for inducing variability in sesame and advantageous in increasing the pollen viability.

Pollen Morphology of the Genus Tragopogon (Asteraceae)

Tragopogon L. (Cichorioideae, Lactuceae, Scorzonerinae) is an Old World genus with 150 species. Pollen morphology has proved useful in the systematics of some genera and species of Asteraceae as well as in that of some of its genera and species. The pollen morphology of 24 taxa of the genus Tragopogon was investigated in detail by scanning electron microscopy (SEM). The pollen grain type ranged from suboblate, oblate-spheroidal to prolate-spheroidal in equatorial view and hexagonal, obtuse-hexagonal to hexagonal-angular in polar view. In this study separation of the species of the sections Majores, Profundisulcati, Sosnovsky, Chromopappus, Rubriflori according to Flora Iranica is presented from the other species of Tragopogon. T. jezdianus, T. porphyrocephalus, T. rezaiyensis are suggested to belong to Rubriflori section. The results indicate that the palynological characters of the genus Tragopogon are valuable for taxonomic applications and are useful for classification.

Pollen morphology of the genus Impatiens L. (Balsaminaceae) and its systematic implications

Pollen morphology of 18 species from the genus Impatiens collected from different localities in Nilgiris, Tamil Nadu was evaluated using scanning electron microscopy (SEM) during the period of February 2017 to November 2019. From the observation of pollen it was found to be structurally monad; prolate, sub-prolate and prolate-spheroidal in equatorial view; and circular, rectangular, triangular, quinquangular, elliptic and quadrangular in polar view. The apertures varied from dicolpate, tricolpate to tetracolpate. The main ornamentation type was reticulate in most of the species except Impatiens fruticosa which showed echinate ornamentation. The variations in pollen structure within the species were useful for the identification and classification of the genus Impatiens. The high structural diversity renders important taxonomic value for species differentiation.

Scanning electron microscopy observations of pollen morphology in common vetch (Vicia sativa) subspecies

Common vetch (Vicia sativa) is an important forage and green manure crop that is widely cultivated around the world. However, the large number of subspecies and accessions of common vetch has made taxonomic research on this species difficult. Pollen morphology data can provide important evidence in the study of plant phylogeny. Therefore, in this research, light microscopy and scanning electron microscopy were used to observe seven morphological traits of pollens from 22 common vetch accessions, and residual maximum likelihood and pattern analysis was conducted. The results showed that the pollen grains of the 22 accessions were all monad pollen and the polar view revealed three-lobed circular and triangular shapes, while the equatorial view mainly revealed an oblate shape; only one accession showed an oblate spherical shape. All accessions were 3-zonocolporate and the colpus length extended close to the poles. The polar axis length was (19.39 ± 0.97)–(42.12 ± 0.76) μm and the equatorial axis length was (35.97 ± 1.27)–(45.25 ± 0.81) μm. We found that qualitative traits of pollen shape, aperture polar view and ornamentation were highly stable. Among them, polar axis length, equatorial axis length and colpus length and width had significant differences among the accessions. The ratios of the equatorial and polar axes had significant differences among the subspecies. This trait information could be used for the classification and identification of common vetch accessions and subspecies.

Morphology of pollen in Apiales (Asterids, Eudicots)

In this monograph, for the first time, the pollen morphology was analysed in the context of modern taxonomic treatment of the order and statistically evaluated in search of traits that could be utilised in further taxonomic and evolutionary studies. Our research included pollen sampled from 417 herbarium specimens representing 158 species belonging to 125 genera distributed among all major lineages of Apiales. The pollen was mechanically isolated, acetolysed, suspended in pure glycerine and mounted on paraffin-sealed slides for light microscopy investigation. Although most of the analysed traits were highly homoplastic and showed significant overlap even between distantly related lineages, we were able to construct a taxonomic key based on characters that bear the strongest phylogenetic signal: P/E ratio, mesocolpium shape observed in polar view and ectocolpus length relative to polar diameter. All the investigated traits are easy to observe with light microscopy and defined by clear and well-documented typology. Early diverging lineages of Apiales constitute a distinct group due to subprolate pollen grains (P/E ratio < 1.25). Among four subfamilies of Apiaceae, Mackinlayoideae can be easily identified based on a combination of traits shared with Klotzschia and Platysace—enigmatic umbllifers with highly uncertain phylogenetic position. Pollen of Azorelloideae is much more diverse but retains many plesiomorphic traits found in early-diverging Apioideae. In contrast, Saniculoideae and most representatives of Apioideae are characterised by evolutionary advanced morphology (perprolate pollen grains with relatively short ectocolpus and bone-shaped outline in colpus view). However, it remains unclear whether similarities between Saniculoideae and higher apioids are an example of convergent evolution or reflect common ancestry. Pollen of Hermas shows a unique combination of traits some of which are typical for Azorelloideae while others resemble Saniculoideae.

Use of Pollen Morphology Traits for Identifying Species of Centaurea L. Asteraceae in Kurdistan-Iraq

The polleniferous material of Centaurea taxa grow in Kurdistan-Iraq was collected. Samples were tested using scanning electron microscopy (SEM) and light microscopy (LM). In the polar view, pollen grain outlines are mostly triangular or triangular-circular. In equatorial view, the elliptic shape is common, while circulars or semicircular shapes are rare. The exine sculpture is scabrate, and the tectum is perforate. Number of sculpture microspinules/ µm², and their heights together with the number of wall perforations provide significant characters for taxa delimitation. Pollen grains of all species are of medium size, very few of some species pollen are larger or smaller in size. Species producing subprolate pollen shape is common, while oblate spheroidal and Prolate spheroidal shapes are less common. The principal component analysis and the discriminant analysis can recognize 65.478% and 87.54% of the total variability respectively; moreover, the discriminant function can correctly classify 125 or 78.125% out of 160 observations for pollen traits.

Palynomorphological peculiarities of species Hypericum L. (Hypericaceae) of the flora of Ukraine

The palinomorphological features of six species of the genus Hypericum (H. аlpigenum, H. elegans, H. hirsutum, H. maculatum, H. montanum, H. perforatum) of the flora of Ukraine have been investigated. All species studied are valuable medicinal plants. However, only two species of raw material are officially permitted: H. perforatum and H. maculatum. Raw materials of other species can also be harvested from natural habitats, as they are wide spread in some regions of Ukraine and morphologically similar to pharmacopoeial species, but their admixture to the raw materials reduces its quality. The aim of research was to make a comparative morphological analysis of pollen grains six species of genus Hypericum of Ukrainian flora for determine the common and distinctive features that will identify the species of raw materials. We used a scanning electron microscope to investigate the pollen grains ultrascultures (CEM, JSM 6060 LA). The studies were performed according to the standard method. As a result of palynomorphological studies of six species of the genus Hypericum of the flora of Ukraine established, that the pollen grains of the species studied are small-sized, 3-colporate, ellipsoidal or spheroidal, outline in polar view ‒ trilobate, rounded-triangular, in equatorial elliptical. In all studied species the colpi are long, mostly with distinct margins, pointed ends and a granular membrane. The pores are undistinct. Sculpture exine in the investigated species of the genus Hypericum of the flora of Ukraine are microreticulate (H. perforatum, H. alpigenum) and reticulate (all other species studied). Morphometric features of pollen grains of the studied species: the length of the polar axis, equatorial diameter, colpus width, mesocolpium width, the diameter of the apocolpium, the ratio of the length of the polar axis to the equatorial diameter, the ratio of the mesocolpium widths and aperture widths can be used as additional diagnostic features in identification species of the genus Hypericum of Ukrainian flora.