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Exine pattern of Kanieae under scanning electron microscope. Scale bar = 2 mm. (a) Barongia lophandra, (b) Cloezia floribunda, (c) Kania eugenioides, (d) Lysicarpus angustifolius, (e) Mitrantia bilocularis, (f) Ristantia gouldii, (g) R. pachysperma and (h) Sphaerantia chartacea.
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Pollen morphology of 44 genera and 101 species from the Myrtaceae tribes Kanieae, Myrteae and Tristanieae was surveyed using scanning electron microscopy (SEM) and light microscopy (LM). Most Myrteae pollen were brevicolpate and granulate, which is unique within Myrtaceae, and these are most likely ancestral characters for this tribe. Two main poll...
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Context 1
... SEM polar view - Fig. 1a; SEM exine pattern - Fig. 2a; SEM equatorial view - Fig. 4a. SEM: Barongia pollen were tricolporate with a rugulate exine. Pollen sides were straight or convex and colpal morphology was parasyncolpate with arcuate, angular or inverse arcuate colpi. Pollen ambs were round or pointed, colpal edges were broken or smooth and the apocolpial field was scabrate, psilate, ...
Context 2
... pollen studies: Pike (1956); Gadek and Martin (1981). Images: SEM polar view - Fig. 1c; SEM exine pattern - Fig. 2c; LM polar view - Fig. 5c, d. SEM: Kania pollen were tricolporate or occasionally tetracolporate. Pollen sides were concave or sometimes straight, and colpal morphology was parasyncolpate with arcuate colpi. Pollen ambs were round or flat, colpal edges were smooth and visible apocolpial fields were ...
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... pollen studies: Pike (1956). Images: SEM polar view - Fig. 1 day SEM exine pattern - Fig. 2 days; LM polar view - Fig. 5e, f. SEM: Lysicarpus pollen were tricolporate with a rugulate or verrucate/scabrate exine. Pollen sides were concave or straight and colpal morphology was parasyncolpate with angular colpi. Pollen ambs were pointed or notched, colpal edges were round or smooth and the apocolpial field was psilate. Pollen ...
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... pollen studies: none. Images: SEM polar view - Fig. 1e; SEM exine pattern - Fig. 2e; SEM equatorial view - Fig. 4b; LM polar view - Fig. 5g. SEM: Mitrantia pollen were tricolporate with a verrucate or verrucate/scabrate exine. Pollen sides were concave or straight and colpal morphology was parasyncolpate with angular colpi, or less commonly syncolpate. Pollen ambs were pointed, notched or less often flat, colpal edges ...
Context 5
... pollen studies: Gadek and Martin (1982). Images: SEM polar view - Fig. 1f, g; SEM exine pattern - Fig. 2f, g; SEM equatorial view - Fig. 4c; LM polar view - Fig. 5h. SEM: Ristantia pollen were tricolporate with a granulate or granulate/scabrate exine. Pollen sides were concave, convex or straight, and colpal morphology was parasyncolpate with angular colpi. Pollen ambs were round or sometimes pointed, colpal edges were broken, and the ...
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... pollen studies: Pike (1956). Images: SEM polar view - Fig. 1b; SEM exine pattern - Fig. 2b; SEM equatorial view - Fig. 4e; LM polar view - Fig. 5a, b. SEM: Cloezia pollen were tricolporate with a rugulate exine. Pollen sides were deeply concave and colpal morphology was parasyncolpate with arcuate colpi. Pollen ambs were round or pointed, colpal edges were smooth and the apocolpial field was psilate. Pollen length ranged ...
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Pollen morphology of 16 genera and 101 species from the Myrtaceae tribes Backhousieae, Melaleuceae, Metrosidereae, Osbornieae and Syzygieae was surveyed using scanning electron microscopy (SEM) and light microscopy (LM). The most common pollen type observed in these tribes was parasyncolpate with arcuate or angular colpi, and a rugulate exine patte...
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Previous studies reported Psidium as one of the most difficult genera to delimit within the American Myrtaceae. Even though palynology has improved the taxonomy of Angiosperms, information about the usefulness of pollen morphology for taxonomic purposes in Myrtaceae remains contradictory. Here, we investigate the significance of pollen morphology f...
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Citations
... We identified the palynomorphs based on modern reference samples stored at the University of Melbourne, along with published descriptions and keys (Macphail and Hope, 2018;Punt et al., 2007;Thornhill et al., 2012aThornhill et al., , 2012bThornhill et al., , 2012cThornhill et al., , 2012d. The majority of the identification was done at family or genus level, but in some cases to the specie level (Pherosphaera hookeriana, Nothofagus gunnii, Phyllocladus aspleniifolius, Nothofagus cunninghamii, Agastachys odorata, Bauera rubioides, Banksia marginata, Gymnoschoenus sphaerocephalus). ...
... Gadek and Martin (1981) examined Kania pollen by light microscopy only; they confirmed the differences between Kania and Metrosideros but did not detect colpi. Thornhill et al. (2012aThornhill et al. ( , 2012b also confirmed the size difference between the genera but the improved resolution of the scanning electron microscope showed more detail such that Kania pollen could now be described as 'parasyncolpate with arcuate colpi' (Thornhill et al. 2012a, p. 262); however, in general form, Kania pollen was not dissimilar to pollen of species of Lysicarpus and Tristaniopsis Brongn. & Gris, differing only by being obscurely parasyncolpate with a less ornamented exine. ...
... Pollen morphology of Cloezia is neutral on the question of relationships. Thornhill et al. (2012a) found little difference in pollen morphology between Cloezia and the genera of Kanieae sens. lat. ...
... and that there was little difference in pollen morphology between Cloezia and Xanthomyrtus, because both have parasyncolpate pollen that is similar in size and exine pattern. In strong contrast with these taxa, the genera of core Tristanieae (Tristania and Thaleropia) share highly derived pollen that is the smallest found in the family so far (~7 μm in diameter) and is triporate and acolpate with a psilate exine (Pike 1956;Gadek and Martin 1981;Patel et al. 1984 for Tristania; Thornhill et al. 2012a for both genera). ...
The current tribal classification of Myrtaceae was based on analysis of the plastid matK coding region within the trnK intron. The phylogenetic position of the genera Cloezia and Xanthomyrtus was poorly supported, and the original sequence for Kania, the type genus of the tribe Kanieae, was rather poor. To clarify relationships, we sequenced plastid psbA–trnH and an extended portion of the trnK intron, including the spacer regions flanking matK, and nuclear ribosomal ITS and ETS regions for representative species across the tribes, including denser sampling of the three genera of interest. Analyses of these extended datasets show a strong relationship between Kania and the tribe Metrosidereae but not with other genera presently assigned to the Kanieae. The relationship between Kania and the tribe Metrosidereae is strongly correlated with morphological features recently documented in Metrosideros fossils. Consequently, a new tribe, Tristaniopsideae PeterG.Wilson, is described to accommodate most genera presently assigned to Kanieae. Furthermore, the morphological divergence and genetic distance shown by Cloezia and Xanthomyrtus are here considered as justifying their recognition as the tribes Cloezieae Peter G.Wilson and Xanthomyrteae Peter G.Wilson. Recognition of these tribes brings to four the number of tribes absent from present-day mainland Australia. Prior to this study, Metrosidereae was the only tribe in subfamily Myrtoideae that was absent from mainland Australia.
... We consider that the pollen remains attributed to Psidium, both in the Pay-Paso 1 site (Uruguay) and Santa Marta cave (Mexico), should be interpreted with caution. Usually, Psidium pollen grains are tricolpates and occasionally tetracolpates (Thornhill et al., 2012). Those reported from Santa Marta Cave are tetracolpate, apparently the least common form. ...
Guava (Psidium guajava L., Myrtaceae) is a Neotropical fruit that is widely consumed around the world. However, its evolutionary history and domestication process are unknown. Here we examine available ecological, taxonomic, genetic, archeological, and historical evidence about guava. Guava needs full sunlight, warm temperatures, and well-distributed rainfall throughout the year to grow, but tolerates drought. Zoochory and anthropochory are the main forms of dispersal. Guava’s phylogenetic relationships with other species of the genus Psidium are unclear. A group of six species that share several morphological characteristics are tentatively accepted as the Psidium guajava complex. DNA analyses are limited to the characterization of crop genetic diversity within localities and do not account for possible evolutionary and domestication scenarios. A significant amount of archeological information exists, with a greater number and older records in South America than in Mesoamerica, where there are also numerous historical records. From this information, we propose that: (1) the guava ancestor may have originated during the Middle or Late Miocene, and the savannas and semi-deciduous forests of South America formed during the Late Pleistocene would have been the most appropriate ecosystems for its growth, (2) the megafauna were important dispersers for guava, (3) dispersal by humans during the Holocene expanded guava’s geographic range, including to the southwestern Amazonian lowlands, (4) where its domestication may have started, and (5) with the European conquest of the Neotropics, accompanied by their domestic animals, new contact routes between previously remote guava populations were established. These proposals could direct future research on the evolutionary and domestication process of guava.
... This morphology is characteristic of the Myrtaceae family (Erdtman, 1971;Thornhill et al., 2012a) and agrees with earlier observations on Psidium cattleyanum from other locations (Tuler et al., 2017;(Vishwakarma et al., 2021). Dicolporate and tetracolporate morphotypes observed in this work were not described before in P. cattleyanum pollen morphotypes (e.g., Thornhill et al., 2012b;Tuler et al., 2017), although they had been observed frequently within the Family (Erdtman, 1971). Furthermore, heteropolar forms showing a colpus with a circular pattern and pantocolporate grains are here described for the first time in Psidium L. Dicolporate grains are originated from isobilateral tetrads due to two points of contact between neighbor cells (Wodehouse, 1935); tetracolporate and circular colpus formations respond to different events of the tetrahedral tetrads formation associated with the aperture convergence areas as modeled by Ressayre et al. (2002). ...
... The pollen grains presented different average sizes among the Psidium cattleyanum plants, both in our data (Fig. 5) and in previous studies (Thornhill et al., 2012b;Hister and Tedesco, 2016;Tuler et al., 2017;(Vishwakarma et al., 2021)). This variable should be used cautiously when making comparisons between studies as it can be affected by several factors such as laboratory techniques, mounting medium, or the type of the studied material (Mourelle et al., 2016). ...
In apomictic pseudogamous reproduction, the asexual embryo requires a sexual origin of the endosperm for its nutrition; hence, fertilization is necessary for seed development to occur. Male gametophyte functionality in apomictic polyploids is highly variable and often linked to low values of pollen grain viability. This work evaluates pollen grain development and functional attributes in Psidium cattleyanum, a polyploid and apomictic pseudogamic species. We consider pollen grain ontogeny and pollen grain morphology, size, and viability in two ploidy levels, octoploid and heptaploid. Plants with different ploidy levels showed variation in the duration of microsporogenesis and the size of microspores. Microsporogenesis exhibited several abnormalities in all studied plants, but more frequently in heptaploids; cytomixis was detected in meiosis. Psidium cattleyanum pollen grains registered morphotypes typical of the Myrtaceae family and other heteropolar forms that were not previously described for the genus. Pollen grain size was heterogeneous but larger in octoploid plants. Pollen viability was low and varied both intra- and between ploidies; pollen morphotypes contribute differently to pollen viability depending on the ploidy of the plant. Several abnormalities detected during pollen grain ontogeny affect pollen grains performance. Polyploidy is proposed as the leading cause of meiosis abnormalities. Further, variations in pollen grain viability and final pollen size and morphology found in different plants suggest that ploidy levels can affect these attributes differently.
... lucidum and P. molle. Earlier studies of Thornhill [37] and Tuler [39] also indicated that pollen size ranges between 10 and 24 μm. ...
Cryopreservation of pollen is a complementary conservation strategy and can be used for conserve the diversity in the genus Psidium. The present study aims to cryopreserve the pollen of Psidium species to overcome asynchronous flowering. The pollen of different Psidium species were germinated in vitro in an optimized medium of germination. In vitro/in vivo pollen viability assessment and SEM analysis were carried out to determine the changes after cryopreservation. The in vitro pollen viability was determined at monthly intervals starting from fresh pollen until six months of cryopreservation. The in vivo fertility tests were carried out by pollination using both fresh and cryopreserved pollen. The cryopreserved pollen showed in vitro germination ranging from 1.78% (in P. molle) to 81.67% (in “H 12–5”) compared to fresh pollen (2.16% in P. molle to 86.08% in P. guineense). In vivo fertility was tested by controlled pollination using six-month-old cryopreserved pollen and it resulted in fruit setting ranged between 3.33% (P. cattleianum var. cattleianum) and 27.66% (P. chinensis) as compared to fresh pollen between 4.0% (P. cattleianum var. cattleianum) and 30.66% (P. chinensis). Seed set and germination was also recorded in all the crosses attempted using cryopreserved pollen. These in vitro and in vivo results indicated that cryopreservation is an effective technique for breeding and conserving the haploid gene pool in cryo genebank. Scanning Electron Microscopic studies of pollen revealed no significant variation in shape and size after cryopreservation when compared to fresh pollen.
... Regarding the shape of the pollen grain Thornhill et al. (2012) found round pollen grains for C. guazumifolia (Cambess.) O.Berg, differing from the triangular grains found in the species studied. ...
The species Campomanesia adamantium and C. pubescens present a great morphological variability, with the existence of morphotypes and the indication of a possible hybridization process occurring between them. Thus, the aim of this study was to characterize the Campomanesia adamantium species and morphotypes of species Campomanesia pubescens through palynological reviews and with the use of molecular markers to assist the taxonomic description of the species. The plant material was collected in the experimental field of Federal University of Jataí, in bloom of 2014, and analyzes were performed in the Morphology Laboratory of Plant Taxonomy and in the Laboratory of Genetics and Plant Breeding belonging to the same institution. Analysis of scanning electron microscopy was performed at the Federal University of Lavras. Important information was found that reinforce the possibility of cross between Campomanesia adamantium and Campomanesia pubescens, generating morphotypes intermediaries, indicating a possible hybridisation process. It can be concluded that Campomanesia adamantium is farthest from the morphotype 2 from Campomanesia pubescens, and morphotypes 1 and 3 are intermediate between them, possibly being hybrids.
... Gomidesia (Lucas In the latter, possibly due to uneven growth of the connective (Vasconcelos et al. 2017a), locule wall retraction is not always complete, giving a poricidal aspect associated with adaptation to buzz pollination (Proença 1992;Nic Lughadha 1998). Pollen grains are small to medium sized, usually ranging from 14 mm to 22 mm (except Octamyrtus, where pollen grains are up to 44 mm; Thornhill et al. 2012), triangular shaped and brevicolpate, with little variation among most Myrteae lineages (see review by Thornhill et al. 2012). ...
... Gomidesia (Lucas In the latter, possibly due to uneven growth of the connective (Vasconcelos et al. 2017a), locule wall retraction is not always complete, giving a poricidal aspect associated with adaptation to buzz pollination (Proença 1992;Nic Lughadha 1998). Pollen grains are small to medium sized, usually ranging from 14 mm to 22 mm (except Octamyrtus, where pollen grains are up to 44 mm; Thornhill et al. 2012), triangular shaped and brevicolpate, with little variation among most Myrteae lineages (see review by Thornhill et al. 2012). ...
With ca. 2500 species, Myrteae is the largest tribe of Myrtaceae and one of the most diverse groups of flowering plants in the tropical Americas. In light of recent systematics adjustments, the present study is a review and provides new insights into floral diversity and evolution in Myrteae. General aspects of floral ontogeny and morphology for the fifty currently accepted genera plus all accepted sections within the large genera Eugenia and Myrcia are summarized based on current morphological data. The discussion provides a broader understanding of the floral diversity across the tribe, highlighting developmental modes, ecological traits, and specializations in reproductive strategies. Hypotheses to be tested in future studies are also presented and discussed.
... Triangular in polar view, with apertures at the angles and elliptic in equatorial view. Small to medium size (28)(29)(30). According to Silva et al. (31), pollen grains of this family are peroblates to suboblates, isopolar or hetero-polar, radial and with exine perforated or psilate. ...
This study aimed to characterize species of Myrtaceae belonging to genera already identified in the pollen spectrum of beehive products of social bees, describing pollen grains morphology and correlating with taxonomic differences the species reported in the literature. For each plant species, measurements were made with 25 pollen grains in equatorial view and the polar diameter (PD) and equatorial diameter (ED) were measured. The exine thickness was obtained by measuring 10 pollen grains in polar view at the medium height of mesocolpium. The description of pollen morphology showed that pollen grains of the species are triangular amb, 3-colporates, psilate surface, small to medium size and oblate shape with the P/E ratio ranging from 0.52 to 0.72 µm. The morphological description of Myrtaceae species showed similarity between several characteristics common to pollen grains of this species. The description also allowed separation of nine species studied by size and specific morphological characters with the identification key, which can also be used to study the pollen spectrum of hive products.
... Pollen was identified by reference to the author's modern pollen reference collection, published manuals [41][42][43][44][45], published studies of individual families, e.g. [33,46,47], and the Australasian Pollen and Spore Atlas (available at apsa.anu.edu.au). Pollen was counted on transects until a pollen sum of 500-600 was achieved. ...
Pollen analysis is widely used to verify the geographic origin of honeys, but has never been employed in Australia. In this study, we analysed the pollen content of 173 unblended honey samples sourced from most of the commercial honey producing regions in southern Australia. Southern Australian vegetation is dominated by Eucalyptus (Myrtaceae) forests and, as expected, most Australian honeys are palynologically dominated by Eucalyptus, while other important components include Myrtaceae taxa such as Corymbia/Angophora and the tribe Leptospermeae; plus Brassicaceae, Echium, Macadamia, and Acacia. An important feature of the honeys is the number of Myrtaceae pollen morphotypes per sample, which is generally high (mean = 4.6) compared to honeys produced outside of Australia, including Eucalyptus honeys produced in the Mediterranean region, and honeys produced in South America, which has its own rich indigenous Myrtaceae flora. In the latter regions, the number of Myrtaceae morphotypes is apparently generally ≤2. A high number of Myrtaceae morphotypes may be a feasible criterion for authenticating the origin of Australian honeys, since most Australian honey is produced by honey bees mainly working indigenous floral resources. Myrtaceae morphotype diversity is a convenient melissopalynological measure that could be applied even where detailed knowledge of the pollen morphology of the many component genera and species is absent. Palynological criteria developed in Europe for authenticating Eucalyptus honeys should not be relied upon for Australian honeys, since those criteria are not based on samples of Australian honey.
... Barth and Barbosa (1972) reported that pollen grains are sincolpate, polar regions are devoid of sexine. Furthermore, Thornhill (2012) described feijoa pollen as tricolporate, with a granulate/scabrate exine, colpal morphology was parasyncolpate, length from 15.5 μm to 19.9 μm, width 15.1 μm to 17.9 μm, and colpus length 5.5 μm to 8.1 μm. ...
Pollination is a key reproductive event conducive to fruit set in Feijoa (Acca sellowiana). Flowers are uniflorous, often forming clusters and hermaphrodite, bearing stamens and one elongated carpel. Stamens are numerous ranging from 60 to 120 per flower depending on cultivar. Flowers do not produce nectar. Pollen grains are small with average size of 10–28 μm in diameter. Some cultivars bear barriers to self-fertilization e.g. self-incompatibility and dichogamy by protogyny. Feijoa can be self-pollinated and able to set fruit, or partially, self-fertile. Wind is a possible pollination agent, but more research is required to confirm it as a vector. Cross-pollination occurs among different cultivars. Birds are also reported as important pollinators. Muscicapidae, Turdidae and Thraupidae bird families are important floral visitors. Birds feed on feijoa petals and transfer pollen grains from their body parts to stigma, promoting pollination. Insects, particularly bees are also reported to be pollinators. However, this again is controversial. The small body of bees is unable to establish contact with the stigmatic surface. Experimental pollen germination, viability and tube growth are dependent on cultivar and culture media conditions. Few studies have been conducted on pollen germination. This review seeks to expand the current information on feijoa pollination in tropical and subtropical environments. It is expected that this review will be useful to senior researchers, undergraduate students, growers and the general public.
