Observation Study on Pollen Morphology of Chinese Pennisetum

[Objective] The aim was to study pollen morphology of Pennisetum native species.[Method] We carried out the observation by optical microscope and scanning electron microscope on six materials of pollen grains including three species and three transmogrifications from one variant of Pennisetum native species.[Result] The pollen grains were globose or subglobose.Germination aperture which located at distal side was singular and its circumambience was thickened.Pollen wall which had two layers was thin and easy to be crimpled.There were obvious differences between ektexine ornamentations as well as particle sizes.[Conclusion] The question of low seed-setting rate of Pennisetum native species had relations with the withered pollen morphology to some extent.The differences between pollen morphology as well as ektexine ornamentations accorded with the division of species and variants from Pennisetum.In addition,the relationship between pollen morphology and seed-setting rate provided references to introduce good grass seed and choose breeding parent materials of Pennisetum.

Study on Pollen Morphology of Nine Major Crops in Bashang Plateau of Hebei Province

[Objective] This study aimed to investigate the pollen morphology of nine major crops in Bashang Plateau of Hebei Province. [Method] By using an optical microscope, pollen morphology of nine major crops in Bashang Plateau of Hebei Province was observed and compared. [Result] Pollen grains were spherical, nearly spherical or prolate; pollen grains of Cucurbita pepo were the largest, and those of Brassica campestris were the smallest; P/E value of Vicia faba was the maximum of 1.77, and that of Avena chinsis was the minimum of 1.00; there were six types of germinal apertures, including single-aperture, scattered-aperture, 3-aperture, 3-groove, 3-colporate and 3-4-colporate; there were four types of exine ornamentation, including reticulate ornamentation, warty ornamentation, spinulose ornamentation and granular ornamentation. [Conclusion] This study not only provided standard maps and related information for the identification of crop pollens in different strata, but also provided modern palynological evidence for extracting information of synarthropic plants （cultivated crops mostly） in different strata, deducing the natural environment ancient human lived in, and understanding the relationship between human and environmental changes.

Pollen morphology of Rhododendron subgen. Tsutsusi and its systematic implications

Eighty-four pollen samples were obtained for 80 taxa, of which, 13 species and one variety are from sect. Brachycalyx Sweet, 58 species and two varieties from sect. Tsutsusi Sweet, and six species from subgen. Pentanthera （G. Don） Pojarkova, respectively. Pollen morphology of all samples was observed using LM and SEM. Pollen grains are revealed to be spheroidal and tetrahedral with tricolporate apertures. Pollen sizes of subgen. Tsutsusi （Sweet） Pojarkova range from 37.67 μm to 61.06μm, and the exine sculptures are more or less compactly granulated. Pollen sizes are significantly different between sect. Brachycalyx and sect. Tsutsusi of subgen. Tsutsusi. Rhododendron tashiroi Maxim. of sect. Tsusiopsis Sleumer shows a close affinity to sect. Brachycalyx. Pollen size and exine are consistent with general morphology in differentiating species in sect. Tsutsusi. Rhododendron huadingense B. Y. Ding ＆ Y. Y. Fang, once placed as a member of sect. Brachycalyx, should be considered as a species in subgen. Pentanthera.

Pollen Morphology of Artemisia L. and Its Systematic Significance

The pollen of 57 species representing 7 sections ofArtemisia was examined by light microscope and scanning microscope for the purpose to elucidate the systematic relationships of the genus. The examination indicates that the pollen grains present high concordance which is characterized by the globular or the approximate shape, 3-lobed circular from polar view while granular or ellipse sphere from tropical plate with tricolporate structure. The exine of pollen has an obvious double structure of inner and outer layers (including the tectum and columnar layers) where the outer is thicker than the inner and the sculpture of exine degenerates into small spinules easily distinguishable from other genera of the Compositae. Based on exine sculpture. the pollen grains ofArtemisia can be divided into two types: Myriantha type and Mongolica type, which possesses 4 subtypes according to the distribution forms of spinule: (1) Sacrorum subtype, (2) Oligocarpa subtype, (3) Lavandulaefolia subtype, (4) Anomale subtype.

Pollen morphology in Saxifraga(Saxifragaceae) from Ny-Alesund, Svalbard, Arctic, and its taxonomic significance

Pollen morphology of eight species of Saxifraga, i.e.S, cespitosa, S. oppositifolia, S. cernua, S. nivalis, S. aizoides, S. rivularis, S. hieraciifolia, and S. hirculus, collected from Ny-Alesund, Svalbard, Arctic was examined using light and scanning electron microscopy. Pollen grains of Saxifraga species are subprolate or prolate, 3-colpate, 15.4-44.4 μm in the polar axis, 11.4 34.6 μm in the equatorial axis, and show a P/E ratio 1.19-1.40. On the basis of exine ornamentation, four pollen types, viz., the S. oppositifolia type （striate without scabrae on the muff）, S. cernua type （striate with scabrae on the muri）, S. nivalis type （microreticulate and operculum absent）, and S. cespitosa type （microechinate and operculum present）, were recognized. Hierarchical cluster analysis of the pollen morphological characters indicated that pollen morphology supports the infrageneric classification of the genus Saxifraga.

Pollen Morphology and Ecological Significance of Nine Hygrophyte Species at Sevenstar Lake Area in the Bashang Area of Hebei Province

ObjectiveThis study aimed to investigate the morphological characteristics of pollen from nine hygrophyte species at Sevenstar Lake area in the Bashang Area （the southern edge of Inner Mongolian Plateau） of Hebei Province, as well as their ecological significance. MethodThe pollen morphology of nine hygrophyte species distributed at Seven Star Lake area was observed and studied by using an optical microscope, and morphological characteristics like size, shape, surface ornamentation were recorded. ResultsPollen grains were globose, subglobose prolate spheroidal; germination aperture had five types, namely, 3-groove, 6-groove, 3 （4）-groove, 3-colporate, 3 （4）-colporate; ektexine possessed four kinds of ornamentation： reticulate, striped, spiny, granular. Meanwhile, the environmental indication significance of these nine hygrophyte species was also discussed according to their habitats, origin and distribution. ConclusionThe study provides the basis of modern palynology for the study of ancient environment, ancient vegetation and paleoclimate.

Pollen morphology of the genus Cornukaempferia (Zingiberaceae) in Thailand

Cornukaempferia is a recently described genus of Zingiberaceae which only occurs in Thailand as a rare genus with limited geographical distribution. Only three species have been described so far, including a recently described new species, C. larsenii. These three species are morphologically very similar and additional data on other biological aspects are useful for the elucidation of their relationship. Pollen morphology of all three species of genus Cornukaempferia has been studied by light microscopy and scanning electron microscopy. The pollen grains are monad, spherical, inaperturate. The exine sculpture is echinate with psilate between the spines for C. aurantiflora and C. longipetiolata, or echinate with regulate between the spines for C. larsenii. This observation helps support the taxonomic status of C. larsenii.

Pollen morphology of selected tundra plants from the highArctic of Ny-lesund, Svalbard

Documenting morphological features of modem pollen is fundamental for the identification of fossil pollen, which will assist researchers to reconstruct the vegetation and climate of a particular geologic period. This paper presents the pollen morphol- ogy of 20 species of tundra plants from the high Arctic of Ny-Alesund, Svalbard, using light and scanning electron microscopy. The plants used in this study belong to 12 families： Brassicaceae, Caryophyllaceae, Cyperaceae, Ericaceae, Juncaceae, Papav- eraceae, Poaceae, Polygonaceae, Ranunculaceae, Rosaceae, Salicaceae, and Scrophulariaceae. Pollen grain shapes included： spher- oidal, subprolate, and prolate. Variable apertural patterns ranged from 2-syncolpate, 3-colpate, 3-（-4）-colpate, 3-（-5）-colpate, 3-colporate, 5-poroid, ulcerate, ulcus to pantoporate. Exine ornamentations comprised psilate, striate-perforate, reticulate, mi- croechinate, microechinate-perforate, scabrate, granulate, and granulate-perforate. This study provided a useful reference for com- parative studies of fossil pollen and for the reconstruction of paleovegetation and paleoclimate in Svalbard region of Arctic.

Classification of Chinese Wintersweet (Chimonanthus praecox) Cultivars Supported by Pollen Morphology

To classify the Chinese wintersweet（Chimonanthus praecox） cultivars and to study their evolution based on pollen morphology.Pollens of 12 representative wintersweet cultivars were examined by scanning electron microscopy（SEM）.Q-cluster analysis was carried out based on the observation results.Results are as follows：（1） The pollen grains were 2lobed circular in polar view,elliptic in equatorial view.The pollen shapes were spheroidal or super-spheroidal by P/E（polar axis length/equatorial axis length） criteria.（2） According to pollen exine ornamentation,it was indicated that white wintersweet is most original.Yellow floral group could be classified into three subgroups：purple-hearted,halo-hearted and yellow-hearted type.Their evolutionary relationship was purple-hearted halo-hearted yellow-hearted.（3） Different wintersweet cultivars showed a different exine sculpture.Palynological analysis could be used in the classification of wintersweet cultivars.The result of cluster analysis indicated that the cultivars could be classified into three groups with a similarity coefficient of 0.41.Each group had similar pollen exine sculpture.It was found that the palynological classification coincided well with morphological classification.Our results support the suggestion that purple streaks or patches of inner-petals should be served as the first-order criteria in wintersweet classification.

Pollen morphology and trichome types of Betula spp. in the Hyrcanian forests of northern Iran

Pollen and trichome morphology of the genus Betula were evaluated from three main habitats in Iran using light and electron microscopy.Pollen types were identical and tri-porate;however,in terms of quantitative data,some differences were observed in exine(outside)wall thickness,length of polar axis and length of equatorial axis,possibly due to the environment.Pollen alone is insufficient to separate species of Iranian birch.Investigation of the trichome trait(small hairs or other outgrowths)revealed that birch species in Iran belong to:(1)Betula litwinowii Doluch.according to the low density of trichomes on the adaxial surface of the leaves and the lack of trichomes on the abaxial surface and many trichomes on the petioles;(2)Betula pendula Roth.due to the absence of trichomes on the adaxial surface and the low density of trichomes on the abaxial surface;and,(3)in the adaxial and abaxial surfaces of leaves and petioles,the trichomes had different types of pilose(long,soft hairs),and this strengthens the possibility of a different species or more likely a hybrid of B.pendula.

Pollen Morphology and Pollen Fertility Estimation of Three Medicinal Plant Species of <i>Hypericum</i>L. from Kaghan Valley, Northern Pakistan

Pollen morphology & pollen fertility estimation of three medicinal species belonging to genus Hypericum L. from flora of Kaghan valley, Northern Pakistan was investigated by light and scanning electron microscopy for the first time. The species are Hypericum elodeoides Choisy in, Hypericum oblongifolium Choisy, and Hypericum perforatum L. Pollen morphological characteristics with considerable variation are provided for these taxa. Among the studied taxa, the pollen grains were 3-4 colporate type and the largest pollen size was found in H. oblongifolium in polar view 23.0 μm and in equatorial view was 25.35 μm. The smallest pollen was of H. elodeoides in polar view which was 19.91 μm and in equatorial view was observed 12.53 μm in H. perforatum. The shape of the all pollen grain was circular to semi-angular in polar view, however in equatorial view the shape of the grains was oblate-spheroidal, in H. elodeoides, and H. oblongifolium while prolate in H. perforatum. Exine sculpturing was observed by scanning electron microscopy which showed foveolate sculpturing in H. elodeoides, reticulate in H. oblongifolium and scabrate in H. perforatum. Pollen fertility estimation ranged from 82.66% to 90.90% which shows that flora of selected species is well established.

Pollen Morphology of Tribes Gnaphalieae, Helenieae, Plucheeae and Senecioneae (Subfamily Asteroideae) of Compositae from Egypt

POLLEN morphology of twenty five species representing 12 genera of tribes Gnaphalieae, Helenieae, Plucheeae and Senecioneae (Asteroideae: Asteraceae) was investigated using light and scanning electron microscopy. The genera are Phagnalon, Filago, Gnaphalium, Helichrysum, Homognaphalium, Ifloga, Lasiopogon, Pseudognaphalium, Flaveria, Tagetes, Sphaeranthus and Senecio. Two pollen types were recognized viz. Senecio pollen type and Filago pollen type. Description of each type, a key to the investigated taxa as well as LM and SEM micrographs of pollen grains are provided.

Pollen morphology of some Tunisian species from genus of Trigonella L.

The pollen morphology of lbur species from the genus Trigonella L. （Fabaceae） distributed in Tunisia （T. foenum-graecum, T. maritima, T. stellata and T. monspeliaca） was studied with light and scanning electron microscope （SEM）. Results showed that the pollen morphology of these four species was not homogenous in relation to shape, dimensions and ornamentation. The pollen grains were 3-zonocolporate, radially symmetrical, isopolar, prolate to perprolate type （P/E = 1.45-2.09）. Medium in size, elliptical or rectangular-obtuse-convex in equatorial view and circular in polar view. Ectoapertures-colpi： long, medium width, with acute ends, endoapertures-pork large, circular to lolongate, protruding in mesocolpium. The rectum was reticulate to perforate reticulate with ± irregular pattern of muri, except for T. monspeliaca which ornamentation was relatively homogeneous with a loose network and psilate area. Ornamentation with lumina different in size was most clearly expressed in mesocolpium while the apocolpium and the area just along the apertures was psilate or with small scattered puncta. The exine thickness was 1.10-2.42 μtm.

Morphological and cytological assessments reveal pollen degradation causes pollen abortion in cotton cytoplasmic male sterility lines

Background Understanding the mechanism of male sterility is crucial for producing hybrid seeds and developing sterile germplasm resources.However,only a few cytoplasmic male sterility(CMS)lines of cotton have been produced due to several challenges,like inadequate variation of agronomic traits,incomplete sterility,weak resilience of restorer lines,and difficulty in combining strong dominance.Therefore,the morphological and cytological identification of CMS in cotton will facilitate hybrid breeding.Results Two F_(2) segregating populations of cotton were constructed from cytoplasmic male sterile lines(HaA and 01A,maternal)and restorer lines(HaR and 26R,paternal).Genetic analysis of these populations revealed a segregation ratio of 3:1 for fertile to sterile plants.Phenotypic analysis indicated no significant differences in traits of flower bud development between sterile and fertile plants.However,sterile plants exhibited smaller floral organs,shortened filament lengths,and anther atrophy on the flowering day in comparison with the fertile plants.When performed scanning electron microscopy(SEM),the two F_(2) populations revealed morphological variations in the anther epidermis.Cellular analysis showed no significant differences in pollen development before pollen maturation.Interestingly,between the pollen maturation and flowering stages,the tapetum layer of sterile plants degenerated prematurely,resulting in abnormal pollen grains and gradual pollen degradation.Conclusion The results of this study suggest that fertility-restoring genes are controlled by a single dominant gene.Sterile plants exhibit distinctive floral morphology,which is characterized by stamen atrophy and abnormal anthers.Pollen abortion occurs between pollen maturity and flowering,indicating that premature tapetum degradation may be the primary cause of pollen abortion.Overall,our study provides a theoretical basis for utilizing CMS in hybrid breeding and in-depth investigation of the dominant configuration of cotton hybrid combinations,mechanisms of sterility,and the role of sterile and restorer genes.

Pollen Morphology of the Platycodonoid Group (Campanulaceae s.str.) and Its Systematic Implications

In this study, we examined the pollen morphology of the platycodonoid group in Campanulaceae s. str. using a scanning electronic microscope. We used pollen grains of 25 accessions representing 24 species of the Codonopsis complex （including Campanumoea, Cyclocodon, Leptocodon, and all three subgenera of Codonopsis）, which is extremely controversial among authors for taxonomic treatment. Pollen morphology of all the other genera in the group observed by previous authors is taken into account in our discussion. A total of nine pollen types with two subtypes in the group were recognized and named for the first time. Molecular and morphological data imply that each pollen type corresponds to a natural group at generic level, and thus the mergence of Leptocodon with Codonopsis and the restoration of Cyclocodon as a separate genus are justifiable, and Codonopsis subg. Pseudocodonopsis, subg. Obconicicapsula, and two species of Codonopsis subg. Codonopsis （C. purpurea and C. chimiliensis） may be better classified as three independent genera separate from the core Codonopsis.

Pollen Morphology of Pedicularis sect.Cyathophora,a Group Endemic to the Eastern Himalaya-Hengduan Mountains Region

Pedicularis sect. Cyathophora is a distinctive group endemic to the eastern Himalaya-Hengduan Mountains region. It was regarded as a ＇grex＇ or section and included all four general corolla types of Pedicularis. A unique feature of it is that the leaf and bract bases are fused together to form a cup-like structure around the stem at each node. Pollen morphology of seven species in sect. Cyathophora was investigated by scanning electron microscopy （SEM） and light microscopy （LM）. Two different pollen apertures could be distinguished （i.e. trisyncolpate and bisyncolpate） using LM, while examination with SEM made it possible to recognize three types of exine ornamentation （i.e. microscabrate, microfoveolate and microreticulate）. The microfoveolate exine ornamentation was found in trisyncolpate pollen grains for the first time. Possible relationships between pollen data and the corolla types were discussed. Comparisons of floral and phyllotaxy characters of the genus Pedicularis, together with the pollen characters of sect. Cyathophora, could help us to better understand the evolutionary trends in Pedicularis.

Pollen Morphology of Parnassia L. （Parnassiaceae） and Its Systematic Implications

: The pollen morphology of 28 species of Parnassia L. was investigated with light microscopy and scanning electron microscopy (SEM). The shape of pollen grains in this genus varies from subspheroidal to prolate in equatorial view and is three-lobed circular in the polar view. Pollen grains are usually radially symmetrical, isopolar, tricolporate or syntricolporate, with reticulate sculpture. The pollen characteristics among species are fairly similar to each other. Morphological information regarding the pollen grains shows that Parnassia is a natural genus. Based on exine ornamentation observed under SEM, three types of pollen grains were recognized: (i) type I, with foveolate-reticulate sculpture; (ii) type II, with a finely reticulate sculpture; and (iii) type III, with a coarsely reticulate sculpture. Most sections of this genus have one type of sculpture of pollen morphology, but Sect. Nectarotrilobos has three types of sculpture and Sect. Saxifragastrum has two types of sculpture. All three types of sculpture can be found in Southwest China, with species with the longest (Parnassia delavayi Franch.) and shortest (Parnassia faberi Oliv.) colpi, implying that Southwest China is the center of diversification of the genus.

Pollen Morphology of Eight Genera of the Subtribe Mutisiinae Less. sensu Bremer （Compositae） from Asia

The pollen morphology of 28 species and one variety representing eight genera of the subtribe Mutisiinae Less. sensu Bremer （Compositae） was investigated by scanning electron microscopy （SEM） and light microscopy. The pollen grains are usually radically symmetrical, isopolar, and tricolporate. The shape varies from spheroidal to subprolate in equatorial view and is three-lobed circular in polar view. Based on exine sculpturing observed under SEM, the pollen grains can be divided into three types： （i） type Ⅰ, with macrogranulate sculpture; （ii） type Ⅱ, with a finely granulate sculpture; and （iii） type Ⅲ with spiny sculpture. The palynological data showed that the Macroclinidium Maxim. was remarkably distinguished from those of the other seven genera. The variation of pollen characteristics within the Mutisiinae in Asia is little at species level, but it proves some useful information for studying the relationships among genera and it has an important significance in further understanding the evolutionary history of Mutisiinae.

Observation and Comparison of Pollen Submicroscopic Morphology of Seven Mulberry(Morus alba Linn.) Cultivars

[Objective] This study aimed to investigate the submicroscopic structure and morphological characteristics of mulberry pollen. [Method] Mulberry pollen of seven cultivars were treated by glutaraldehyde fixing, alcohol gradient dehydration, freeze-drying and metal plating to observe the size and surface ornamentation under the scanning electron microscope （SEM）. [Result] The pollen surface characteristics and ornamentation were clearly visible, indicating that this method is suitable for SEM observation of mulberry pollen; experimental mulberry pollen was nearly spher- ical, with two germination apertures and processes on aperture membrane; polar axis was 15.99-22.63 μm long, and equatorial axis was 14.98-20.78 μm long; the pollen volume of ＂Yu No.2＇ was the maximum, while that of ＂Jinxuan No.7＇ was the minimum; the surface of mulberry pollen showed smooth and tumor-like protuberance ornamentations, covered with different densities of particles. [Conclusion] Glutaralde- hyde fixative-alcohol gradient dehydration is an ideal method for morphological char- acteristics of mulberry pollen. This study may provide useful information for palynology identification of Morus plants or even species-level systematic classification.

Pollen Morphology of Tundra Shrubs and Submarginal Plants from Barrow, Alaska

Investigation of plant morphological features, pollen, and habitat have been made for two shrub species from Barrow, Alaska, namely Dryas integrifoila M. Vahl and Salix rotundifolia Trautv., both of which are endemic to the Arctic floristic area. The former species has small lanceolate or plate leaves, whereas the latter has rounded leaves with distinct veins, rich in vitamin C. Both have dwarf and sprawling habits. Pollen studies showed that the pollen grains of the two species are spheroidal to sub-spheroidal or prolate. The type of aperture was tricolporate; pollen size 26.3-31.3 μm; ornamentation finely reticulate under a light microscope （LM） and strlate-reticulate under a scanning electron microscope （SEM） for D. integrafoila and finely reticulate under the LM and SEM for S. rotundifolia. Comparisons were made between the pollen from the same species from Arctic collections with those from China and Japan. Investigation of pollen morphology of tundra plants can provide significant data for comparative studies of fossil pollen and for the reconstruction of paleovegetation and paleoclimate in the Barrow area.