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 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.

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.

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.

The morphological diversity of pollen in the genus Gossypium

Background Plant pollen has diverse morphological characteristics that can be consistently passed down from generation to generation.Information on pollen morphology is thus immensely important for plant classification and identification.In the genus Gossypium,however,in-depth research on pollen morphology is lacking,with only few reports on limited cotton species.To evaluate the diversity of pollen in Gossypium,we therefore conducted a comprehensive analysis of the pollen morphology of 33 cotton species and varieties using scanning electron microscopy.Results The 33 analyzed cotton samples exhibited common pollen morphological features,including spherical shapes,radial symmetry,echination,panporation,and operculation,while the pollen size,spine shape,spine density and length showed distinctive features.Pollen size varied significantly among species,with diameters ranging from62.43 μm in G.harknessii to 103.41 μm in G.barbadense.The exine had an echinate sculptural texture,and spines were mostly conical or sharply conical but occasionally rod-like.Spine density varied from 173 in G.incanum to 54 in G.gossypioides,while spine length ranged from 3.53 μm in G.herbaceum to 9.47 μm in G.barbadense.In addition,the 33cotton species and varieties were grouped at a genetic distance of 3.83 into three clusters.Cluster Ⅰ comprised five allotetraploid AD-genome cotton species,four D-genome species,and one K-genome species.Cluster Ⅱ included 13diploid species from A,B,D,E,and G genomes,whereas Cluster Ⅲ only consisted one E-genome species G.incanum.Conclusions Although pollen characteristics alone are not enough to resolve taxonomic and systematic relationships within the genus Gossypium,our results add to knowledge on palynomorphology and contribute to phenological information on these taxa.Our findings should aid future systematic and phylogenetic studies of the Gossypium genus.

Glycosmis longipetala F.J.Mou & D.X.Zhang,a new species of Rutaceae from China

Glycosmis longipetala F. J. Mou ＆ D. X. Zhang is described from Guangxi and Yunnan provinces in southwestern China. The new species is similar to G. cochinchinensis （Lour.） Pierre ex Engl. by its simple leaves, but distinguishable in having long-elliptic or oblanceolate （vs. ovate） leaves, long-ovoid to ellipsoid （vs. ovoid） floral buds, ovaries with many tubercles （vs. smooth） and glabrous （vs. pubescent） stamens. The pollen grains of the new species are 23.9±3.09 （20.8-27.0）×22.0±1.80 （20.4-24.4）μm in size with reticulate exine ornamentation in equatorial area and foveolate in polar area. The chromosome number of the new species is 2n=72.

Staying alive on an active volcano:80 years population dynamics of Cytisus aeolicus(Fabaceae)from Stromboli(Aeolian Islands,Italy)

Cytisus aeolicus is a narrow endemic species restricted to the Aeolian archipelago(SE Tyrrhenian Sea,Italy)and it is one of the most evolutionarily isolated plants in the Mediterranean flora.Historical and literature data suggest that both metapopulations and isolated individuals of C.aeolicus are gradually shrinking.Field investigations and drone images demonstrate that the C.aeolicus metapopulation from Stromboli experienced a strikingly fast increase during the last decades.As of 2019,more than 7000±3000 mature individuals occur on Stromboli,i.e.14 to 20 times more than those counted during the last census,25 years ago.The diachronic analysis of aerial photos concerning last 80 years and the analysis of the growth rings of some selected plants pointed out that the surface occupied,the demographic structure and the distribution pattern of the subpopulations of Stromboli has been highly fluctuating during last decades.Moreover,data issuing from field observations in permanent plots placed in a transect between two isolated mature individuals showed that,under natural conditions,the germination rate of the seedlings of C.aeolicus can be very high and their establishment rate may exceed 40%.By contrast,seedlings mortality is subject to strong annual fluctuations.Additionally,the pollen morphology of the Strombolian metapopulation of this rare and isolated species is studied here for the first time.Contrary to what is stated in recent literature,the C.aeolicus metapopulation from Stromboli is healthy and very dynamic,albeit frequently damaged by the volcanic activity.Regular and repeated field surveys carried out during 3 years(2017-2019)allowed improving our knowledge on the life cycle of C.aeolicus and a new extinction risk assessment of the species,according to IUCN criteria,is presented.